diff --git a/client/src/main/java/envoy/client/Main.java b/client/src/main/java/envoy/client/Main.java
index d64d075..626d7d5 100644
--- a/client/src/main/java/envoy/client/Main.java
+++ b/client/src/main/java/envoy/client/Main.java
@@ -7,8 +7,8 @@ import envoy.client.ui.Startup;
 /**
  * Triggers application startup.
  * <p>
- * To allow Maven shading, the main method has to be separated from the
- * {@link Startup} class which extends {@link Application}.
+ * To allow Maven shading, the main method has to be separated from the {@link Startup} class which
+ * extends {@link Application}.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
@@ -25,8 +25,7 @@ public final class Main {
 	/**
 	 * Starts the application.
 	 *
-	 * @param args the command line arguments are processed by the
-	 *             client configuration
+	 * @param args the command line arguments are processed by the client configuration
 	 * @since Envoy Client v0.1-beta
 	 */
 	public static void main(String[] args) {
diff --git a/client/src/main/java/envoy/client/data/Cache.java b/client/src/main/java/envoy/client/data/Cache.java
index e638f7b..aef6454 100644
--- a/client/src/main/java/envoy/client/data/Cache.java
+++ b/client/src/main/java/envoy/client/data/Cache.java
@@ -35,7 +35,9 @@ public final class Cache<T> implements Consumer<T>, Serializable {
 	}
 
 	@Override
-	public String toString() { return String.format("Cache[elements=" + elements + "]"); }
+	public String toString() {
+		return String.format("Cache[elements=" + elements + "]");
+	}
 
 	/**
 	 * Sets the processor to which cached elements are relayed.
@@ -52,7 +54,8 @@ public final class Cache<T> implements Consumer<T>, Serializable {
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public void relay() {
-		if (processor == null) throw new IllegalStateException("Processor is not defined");
+		if (processor == null)
+			throw new IllegalStateException("Processor is not defined");
 		elements.forEach(processor::accept);
 		elements.clear();
 	}
@@ -62,5 +65,7 @@ public final class Cache<T> implements Consumer<T>, Serializable {
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public void clear() { elements.clear(); }
+	public void clear() {
+		elements.clear();
+	}
 }
diff --git a/client/src/main/java/envoy/client/data/CacheMap.java b/client/src/main/java/envoy/client/data/CacheMap.java
index cf9d501..4d850a1 100644
--- a/client/src/main/java/envoy/client/data/CacheMap.java
+++ b/client/src/main/java/envoy/client/data/CacheMap.java
@@ -4,8 +4,7 @@ import java.io.Serializable;
 import java.util.*;
 
 /**
- * Stores a heterogeneous map of {@link Cache} objects with different type
- * parameters.
+ * Stores a heterogeneous map of {@link Cache} objects with different type parameters.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
@@ -24,7 +23,9 @@ public final class CacheMap implements Serializable {
 	 * @param cache the cache to store
 	 * @since Envoy Client v0.1-beta
 	 */
-	public <T> void put(Class<T> key, Cache<T> cache) { map.put(key, cache); }
+	public <T> void put(Class<T> key, Cache<T> cache) {
+		map.put(key, cache);
+	}
 
 	/**
 	 * Returns a cache mapped by a class.
@@ -34,7 +35,9 @@ public final class CacheMap implements Serializable {
 	 * @return the cache
 	 * @since Envoy Client v0.1-beta
 	 */
-	public <T> Cache<T> get(Class<T> key) { return (Cache<T>) map.get(key); }
+	public <T> Cache<T> get(Class<T> key) {
+		return (Cache<T>) map.get(key);
+	}
 
 	/**
 	 * Returns a cache mapped by a class or any of its subclasses.
@@ -64,5 +67,7 @@ public final class CacheMap implements Serializable {
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public void clear() { map.values().forEach(Cache::clear); }
+	public void clear() {
+		map.values().forEach(Cache::clear);
+	}
 }
diff --git a/client/src/main/java/envoy/client/data/Chat.java b/client/src/main/java/envoy/client/data/Chat.java
index 0683d2d..892b5ca 100644
--- a/client/src/main/java/envoy/client/data/Chat.java
+++ b/client/src/main/java/envoy/client/data/Chat.java
@@ -22,17 +22,19 @@ import envoy.client.net.WriteProxy;
  */
 public class Chat implements Serializable {
 
-	protected final Contact recipient;
-
-	protected transient ObservableList<Message> messages = FXCollections.observableArrayList();
+	protected boolean disabled;
 
 	/**
 	 * Stores the last time an {@link envoy.event.IsTyping} event has been sent.
 	 */
 	protected transient long lastWritingEvent;
 
+	protected transient ObservableList<Message> messages = FXCollections.observableArrayList();
+
 	protected int						unreadAmount;
-	protected static IntegerProperty	totalUnreadAmount	= new SimpleIntegerProperty(0);
+	protected static IntegerProperty	totalUnreadAmount	= new SimpleIntegerProperty();
+
+	protected final Contact recipient;
 
 	private static final long serialVersionUID = 2L;
 
@@ -61,8 +63,12 @@ public class Chat implements Serializable {
 
 	@Override
 	public String toString() {
-		return String.format("%s[recipient=%s,messages=%d]", getClass().getSimpleName(), recipient,
-			messages.size());
+		return String.format(
+			"%s[recipient=%s,messages=%d,disabled=%b]",
+			getClass().getSimpleName(),
+			recipient,
+			messages.size(),
+			disabled);
 	}
 
 	/**
@@ -197,4 +203,22 @@ public class Chat implements Serializable {
 	public void lastWritingEventWasNow() {
 		lastWritingEvent = System.currentTimeMillis();
 	}
+
+	/**
+	 * Determines whether messages can be sent in this chat. Should be {@code true} i.e. for chats
+	 * whose recipient deleted this client as a contact.
+	 *
+	 * @return whether this chat has been disabled
+	 * @since Envoy Client v0.3-beta
+	 */
+	public boolean isDisabled() { return disabled; }
+
+	/**
+	 * Determines whether messages can be sent in this chat. Should be true i.e. for chats whose
+	 * recipient deleted this client as a contact.
+	 *
+	 * @param disabled whether this chat should be disabled
+	 * @since Envoy Client v0.3-beta
+	 */
+	public void setDisabled(boolean disabled) { this.disabled = disabled; }
 }
diff --git a/client/src/main/java/envoy/client/data/ClientConfig.java b/client/src/main/java/envoy/client/data/ClientConfig.java
index acd3216..e15d400 100644
--- a/client/src/main/java/envoy/client/data/ClientConfig.java
+++ b/client/src/main/java/envoy/client/data/ClientConfig.java
@@ -5,8 +5,8 @@ import static java.util.function.Function.identity;
 import envoy.data.Config;
 
 /**
- * Implements a configuration specific to the Envoy Client with default values
- * and convenience methods.
+ * Implements a configuration specific to the Envoy Client with default values and convenience
+ * methods.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
@@ -20,7 +20,8 @@ public final class ClientConfig extends Config {
 	 * @since Envoy Client v0.1-beta
 	 */
 	public static ClientConfig getInstance() {
-		if (config == null) config = new ClientConfig();
+		if (config == null)
+			config = new ClientConfig();
 		return config;
 	}
 
@@ -47,5 +48,7 @@ public final class ClientConfig extends Config {
 	 * @return the amount of minutes after which the local database should be saved
 	 * @since Envoy Client v0.2-beta
 	 */
-	public Integer getLocalDBSaveInterval() { return (Integer) items.get("localDBSaveInterval").get(); }
+	public Integer getLocalDBSaveInterval() {
+		return (Integer) items.get("localDBSaveInterval").get();
+	}
 }
diff --git a/client/src/main/java/envoy/client/data/Context.java b/client/src/main/java/envoy/client/data/Context.java
index a022ac3..2a78b14 100644
--- a/client/src/main/java/envoy/client/data/Context.java
+++ b/client/src/main/java/envoy/client/data/Context.java
@@ -36,7 +36,8 @@ public class Context {
 	 * @since Envoy Client v0.2-beta
 	 */
 	public void initWriteProxy() {
-		if (localDB == null) throw new IllegalStateException("The LocalDB has to be initialized!");
+		if (localDB == null)
+			throw new IllegalStateException("The LocalDB has to be initialized!");
 		writeProxy = new WriteProxy(client, localDB);
 	}
 
diff --git a/client/src/main/java/envoy/client/data/GroupChat.java b/client/src/main/java/envoy/client/data/GroupChat.java
index 188709c..45be856 100644
--- a/client/src/main/java/envoy/client/data/GroupChat.java
+++ b/client/src/main/java/envoy/client/data/GroupChat.java
@@ -2,14 +2,14 @@ package envoy.client.data;
 
 import java.time.Instant;
 
-import envoy.client.net.WriteProxy;
 import envoy.data.*;
 import envoy.data.Message.MessageStatus;
 import envoy.event.GroupMessageStatusChange;
 
+import envoy.client.net.WriteProxy;
+
 /**
- * Represents a chat between a user and a group
- * as a list of messages.
+ * Represents a chat between a user and a group as a list of messages.
  *
  * @author Maximilian K&auml;fer
  * @since Envoy Client v0.1-beta
@@ -25,7 +25,7 @@ public final class GroupChat extends Chat {
 	 * @param recipient the group whose members receive the messages
 	 * @since Envoy Client v0.1-beta
 	 */
-	public GroupChat(User sender, Contact recipient) {
+	public GroupChat(User sender, Group recipient) {
 		super(recipient);
 		this.sender = sender;
 	}
@@ -34,11 +34,14 @@ public final class GroupChat extends Chat {
 	public void read(WriteProxy writeProxy) {
 		for (int i = messages.size() - 1; i >= 0; --i) {
 			final GroupMessage gmsg = (GroupMessage) messages.get(i);
-			if (gmsg.getSenderID() != sender.getID()) if (gmsg.getMemberStatuses().get(sender.getID()) == MessageStatus.READ) break;
-			else {
-				gmsg.getMemberStatuses().replace(sender.getID(), MessageStatus.READ);
-				writeProxy.writeMessageStatusChange(new GroupMessageStatusChange(gmsg.getID(), MessageStatus.READ, Instant.now(), sender.getID()));
-			}
+			if (gmsg.getSenderID() != sender.getID())
+				if (gmsg.getMemberStatuses().get(sender.getID()) == MessageStatus.READ)
+					break;
+				else {
+					gmsg.getMemberStatuses().replace(sender.getID(), MessageStatus.READ);
+					writeProxy.writeMessageStatusChange(new GroupMessageStatusChange(gmsg.getID(),
+						MessageStatus.READ, Instant.now(), sender.getID()));
+				}
 		}
 		unreadAmount = 0;
 	}
diff --git a/client/src/main/java/envoy/client/data/LocalDB.java b/client/src/main/java/envoy/client/data/LocalDB.java
index 13db9df..e3c4ac7 100644
--- a/client/src/main/java/envoy/client/data/LocalDB.java
+++ b/client/src/main/java/envoy/client/data/LocalDB.java
@@ -1,29 +1,34 @@
 package envoy.client.data;
 
+import static java.util.function.Predicate.not;
+
 import java.io.*;
 import java.nio.channels.*;
 import java.nio.file.StandardOpenOption;
 import java.time.Instant;
 import java.util.*;
 import java.util.logging.*;
+import java.util.stream.Stream;
 
 import javafx.application.Platform;
 import javafx.collections.*;
 
-import envoy.client.event.*;
-import envoy.data.*;
-import envoy.data.Message.MessageStatus;
-import envoy.event.*;
-import envoy.exception.EnvoyException;
-import envoy.util.*;
-
 import dev.kske.eventbus.Event;
 import dev.kske.eventbus.EventBus;
 import dev.kske.eventbus.EventListener;
 
+import envoy.data.*;
+import envoy.data.Message.MessageStatus;
+import envoy.event.*;
+import envoy.event.contact.*;
+import envoy.exception.EnvoyException;
+import envoy.util.*;
+
+import envoy.client.event.*;
+
 /**
- * Stores information about the current {@link User} and their {@link Chat}s.
- * For message ID generation a {@link IDGenerator} is stored as well.
+ * Stores information about the current {@link User} and their {@link Chat}s. For message ID
+ * generation a {@link IDGenerator} is stored as well.
  * <p>
  * The managed objects are stored inside a folder in the local file system.
  *
@@ -39,6 +44,7 @@ public final class LocalDB implements EventListener {
 	private IDGenerator				idGenerator;
 	private CacheMap				cacheMap	= new CacheMap();
 	private String					authToken;
+	private boolean					contactsChanged;
 
 	// Auto save timer
 	private Timer	autoSaver;
@@ -68,8 +74,11 @@ public final class LocalDB implements EventListener {
 		EventBus.getInstance().registerListener(this);
 
 		// Ensure that the database directory exists
-		if (!dbDir.exists()) dbDir.mkdirs();
-		else if (!dbDir.isDirectory()) throw new IOException(String.format("LocalDBDir '%s' is not a directory!", dbDir.getAbsolutePath()));
+		if (!dbDir.exists())
+			dbDir.mkdirs();
+		else if (!dbDir.isDirectory())
+			throw new IOException(
+				String.format("LocalDBDir '%s' is not a directory!", dbDir.getAbsolutePath()));
 
 		// Lock the directory
 		lock();
@@ -88,8 +97,7 @@ public final class LocalDB implements EventListener {
 	}
 
 	/**
-	 * Ensured that only one Envoy instance is using this local database by creating
-	 * a lock file.
+	 * Ensured that only one Envoy instance is using this local database by creating a lock file.
 	 * The lock file is deleted on application exit.
 	 *
 	 * @throws EnvoyException if the lock cannot by acquired
@@ -98,17 +106,19 @@ public final class LocalDB implements EventListener {
 	private synchronized void lock() throws EnvoyException {
 		final var file = new File(dbDir, "instance.lock");
 		try {
-			final var fc = FileChannel.open(file.toPath(), StandardOpenOption.CREATE, StandardOpenOption.WRITE);
+			final var fc = FileChannel.open(file.toPath(), StandardOpenOption.CREATE,
+				StandardOpenOption.WRITE);
 			instanceLock = fc.tryLock();
-			if (instanceLock == null) throw new EnvoyException("Another Envoy instance is using this local database!");
+			if (instanceLock == null)
+				throw new EnvoyException("Another Envoy instance is using this local database!");
 		} catch (final IOException e) {
 			throw new EnvoyException("Could not create lock file!", e);
 		}
 	}
 
 	/**
-	 * Loads the local user registry {@code users.db}, the id generator
-	 * {@code id_gen.db} and last login file {@code last_login.db}.
+	 * Loads the local user registry {@code users.db}, the id generator {@code id_gen.db} and last
+	 * login file {@code last_login.db}.
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
@@ -133,10 +143,45 @@ public final class LocalDB implements EventListener {
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public synchronized void loadUserData() throws ClassNotFoundException, IOException {
-		if (user == null) throw new IllegalStateException("Client user is null, cannot initialize user storage");
+		if (user == null)
+			throw new IllegalStateException("Client user is null, cannot initialize user storage");
 		userFile = new File(dbDir, user.getID() + ".db");
 		try (var in = new ObjectInputStream(new FileInputStream(userFile))) {
-			chats		= FXCollections.observableList((List<Chat>) in.readObject());
+			chats = FXCollections.observableList((List<Chat>) in.readObject());
+
+			// Some chats have changed and should not be overwritten by the saved values
+			if (contactsChanged) {
+				final var contacts = user.getContacts();
+
+				// Mark chats as disabled if a contact is no longer in this users contact list
+				final var changedUserChats = chats.stream()
+					.filter(not(chat -> contacts.contains(chat.getRecipient())))
+					.peek(chat -> {
+						chat.setDisabled(true);
+						logger.log(Level.INFO,
+							String.format("Deleted chat with %s.", chat.getRecipient()));
+					});
+
+				// Also update groups with a different member count
+				final var changedGroupChats =
+					contacts.stream().filter(Group.class::isInstance).flatMap(group -> {
+						final var potentialChat = getChat(group.getID());
+						if (potentialChat.isEmpty())
+							return Stream.empty();
+						final var chat = potentialChat.get();
+						if (group.getContacts().size() != chat.getRecipient().getContacts()
+							.size()) {
+							logger.log(Level.INFO, "Removed one (or more) members from " + group);
+							return Stream.of(chat);
+						} else
+							return Stream.empty();
+					});
+				Stream.concat(changedUserChats, changedGroupChats)
+					.forEach(chat -> chats.set(chats.indexOf(chat), chat));
+
+				// loadUserData can get called two (or more?) times during application lifecycle
+				contactsChanged = false;
+			}
 			cacheMap	= (CacheMap) in.readObject();
 			lastSync	= (Instant) in.readObject();
 		} finally {
@@ -145,31 +190,34 @@ public final class LocalDB implements EventListener {
 	}
 
 	/**
-	 * Synchronizes the contact list of the client user with the chat and user
-	 * storage.
+	 * Synchronizes the contact list of the client user with the chat and user storage.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
 	private void synchronize() {
-		user.getContacts().stream().filter(u -> u instanceof User && !users.containsKey(u.getName())).forEach(u -> users.put(u.getName(), (User) u));
+		user.getContacts().stream()
+			.filter(u -> u instanceof User && !users.containsKey(u.getName()))
+			.forEach(u -> users.put(u.getName(), (User) u));
 		users.put(user.getName(), user);
 
 		// Synchronize user status data
 		for (final var contact : user.getContacts())
 			if (contact instanceof User)
-				getChat(contact.getID()).ifPresent(chat -> { ((User) chat.getRecipient()).setStatus(((User) contact).getStatus()); });
+				getChat(contact.getID()).ifPresent(chat -> {
+					((User) chat.getRecipient()).setStatus(((User) contact).getStatus());
+				});
 
 		// Create missing chats
 		user.getContacts()
 			.stream()
 			.filter(c -> !c.equals(user) && getChat(c.getID()).isEmpty())
-			.map(c -> c instanceof User ? new Chat(c) : new GroupChat(user, c))
+			.map(c -> c instanceof User ? new Chat(c) : new GroupChat(user, (Group) c))
 			.forEach(chats::add);
 	}
 
 	/**
-	 * Initializes a timer that automatically saves this local database after a
-	 * period of time specified in the settings.
+	 * Initializes a timer that automatically saves this local database after a period of time
+	 * specified in the settings.
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
@@ -184,68 +232,112 @@ public final class LocalDB implements EventListener {
 		autoSaver.schedule(new TimerTask() {
 
 			@Override
-			public void run() { save(); }
+			public void run() {
+				save();
+			}
 		}, 2000, ClientConfig.getInstance().getLocalDBSaveInterval() * 60000);
 	}
 
 	/**
-	 * Stores all users. If the client user is specified, their chats will be stored
-	 * as well. The message id generator will also be saved if present.
+	 * Stores all users. If the client user is specified, their chats will be stored as well. The
+	 * message id generator will also be saved if present.
 	 *
 	 * @throws IOException if the saving process failed
 	 * @since Envoy Client v0.3-alpha
 	 */
-	@Event(eventType = EnvoyCloseEvent.class, priority = 1000)
+	@Event(eventType = EnvoyCloseEvent.class, priority = 500)
 	private synchronized void save() {
-		EnvoyLog.getLogger(LocalDB.class).log(Level.INFO, "Saving local database...");
+		EnvoyLog.getLogger(LocalDB.class).log(Level.FINER, "Saving local database...");
 
 		// Save users
 		try {
 			SerializationUtils.write(usersFile, users);
 
 			// Save user data and last sync time stamp
-			if (user != null) SerializationUtils
-				.write(userFile, new ArrayList<>(chats), cacheMap, Context.getInstance().getClient().isOnline() ? Instant.now() : lastSync);
+			if (user != null)
+				SerializationUtils
+					.write(userFile, new ArrayList<>(chats), cacheMap,
+						Context.getInstance().getClient().isOnline() ? Instant.now() : lastSync);
 
 			// Save last login information
-			if (authToken != null) SerializationUtils.write(lastLoginFile, user, authToken);
+			if (authToken != null)
+				SerializationUtils.write(lastLoginFile, user, authToken);
 
 			// Save ID generator
-			if (hasIDGenerator()) SerializationUtils.write(idGeneratorFile, idGenerator);
+			if (hasIDGenerator())
+				SerializationUtils.write(idGeneratorFile, idGenerator);
 		} catch (final IOException e) {
-			EnvoyLog.getLogger(LocalDB.class).log(Level.SEVERE, "Unable to save local database: ", e);
+			EnvoyLog.getLogger(LocalDB.class).log(Level.SEVERE, "Unable to save local database: ",
+				e);
 		}
 	}
 
-	@Event(priority = 150)
-	private void onMessage(Message msg) { if (msg.getStatus() == MessageStatus.SENT) msg.nextStatus(); }
+	@Event(priority = 500)
+	private void onMessage(Message msg) {
+		if (msg.getStatus() == MessageStatus.SENT)
+			msg.nextStatus();
+	}
 
-	@Event(priority = 150)
+	@Event(priority = 500)
 	private void onGroupMessage(GroupMessage msg) {
 		// TODO: Cancel event once EventBus is updated
 		if (msg.getStatus() == MessageStatus.WAITING || msg.getStatus() == MessageStatus.READ)
 			logger.warning("The groupMessage has the unexpected status " + msg.getStatus());
 	}
 
-	@Event(priority = 150)
-	private void onMessageStatusChange(MessageStatusChange evt) { getMessage(evt.getID()).ifPresent(msg -> msg.setStatus(evt.get())); }
+	@Event(priority = 500)
+	private void onMessageStatusChange(MessageStatusChange evt) {
+		getMessage(evt.getID()).ifPresent(msg -> msg.setStatus(evt.get()));
+	}
 
-	@Event(priority = 150)
+	@Event(priority = 500)
 	private void onGroupMessageStatusChange(GroupMessageStatusChange evt) {
-		this.<GroupMessage>getMessage(evt.getID()).ifPresent(msg -> msg.getMemberStatuses().replace(evt.getMemberID(), evt.get()));
+		this.<GroupMessage>getMessage(evt.getID())
+			.ifPresent(msg -> msg.getMemberStatuses().replace(evt.getMemberID(), evt.get()));
 	}
 
-	@Event(priority = 150)
+	@Event(priority = 500)
 	private void onUserStatusChange(UserStatusChange evt) {
-		getChat(evt.getID()).map(Chat::getRecipient).map(User.class::cast).ifPresent(u -> u.setStatus(evt.get()));
+		getChat(evt.getID()).map(Chat::getRecipient).map(User.class::cast)
+			.ifPresent(u -> u.setStatus(evt.get()));
 	}
 
-	@Event(priority = 150)
-	private void onGroupResize(GroupResize evt) { getChat(evt.getGroupID()).map(Chat::getRecipient).map(Group.class::cast).ifPresent(evt::apply); }
+	@Event(priority = 500)
+	private void onUserOperation(UserOperation operation) {
+		final var eventUser = operation.get();
+		switch (operation.getOperationType()) {
+			case ADD:
+				Platform.runLater(() -> chats.add(0, new Chat(eventUser)));
+				break;
+			case REMOVE:
+				getChat(eventUser.getID()).ifPresent(chat -> chat.setDisabled(true));
+				break;
+		}
+	}
 
-	@Event(priority = 150)
+	@Event
+	private void onGroupCreationResult(GroupCreationResult evt) {
+		final var newGroup = evt.get();
+
+		// The group creation was not successful
+		if (newGroup == null)
+			return;
+
+		// The group was successfully created
+		else
+			Platform.runLater(() -> chats.add(new GroupChat(user, newGroup)));
+	}
+
+	@Event(priority = 500)
+	private void onGroupResize(GroupResize evt) {
+		getChat(evt.getGroupID()).map(Chat::getRecipient).map(Group.class::cast)
+			.ifPresent(evt::apply);
+	}
+
+	@Event(priority = 500)
 	private void onNameChange(NameChange evt) {
-		chats.stream().map(Chat::getRecipient).filter(c -> c.getID() == evt.getID()).findAny().ifPresent(c -> c.setName(evt.get()));
+		chats.stream().map(Chat::getRecipient).filter(c -> c.getID() == evt.getID()).findAny()
+			.ifPresent(c -> c.setName(evt.get()));
 	}
 
 	/**
@@ -255,14 +347,16 @@ public final class LocalDB implements EventListener {
 	 * @since Envoy Client v0.2-beta
 	 */
 	@Event
-	private void onNewAuthToken(NewAuthToken evt) { authToken = evt.get(); }
+	private void onNewAuthToken(NewAuthToken evt) {
+		authToken = evt.get();
+	}
 
 	/**
 	 * Deletes all associations to the current user.
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	@Event(eventType = Logout.class, priority = 100)
+	@Event(eventType = Logout.class, priority = 50)
 	private void onLogout() {
 		autoSaver.cancel();
 		autoSaveRestart = true;
@@ -289,16 +383,28 @@ public final class LocalDB implements EventListener {
 			// once a message was removed
 			final var messageID = message.get();
 			for (final var chat : chats)
-				if (chat.remove(messageID)) break;
+				if (chat.remove(messageID))
+					break;
 		});
 	}
 
 	@Event(priority = 500)
-	private void onOwnStatusChange(OwnStatusChange statusChange) { user.setStatus(statusChange.get()); }
+	private void onOwnStatusChange(OwnStatusChange statusChange) {
+		user.setStatus(statusChange.get());
+	}
+
+	@Event(eventType = ContactsChangedSinceLastLogin.class, priority = 500)
+	private void onContactsChangedSinceLastLogin() {
+		contactsChanged = true;
+	}
+
+	@Event(priority = 500)
+	private void onContactDisabled(ContactDisabled event) {
+		getChat(event.get().getID()).ifPresent(chat -> chat.setDisabled(true));
+	}
 
 	/**
-	 * @return a {@code Map<String, User>} of all users stored locally with their
-	 *         user names as keys
+	 * @return a {@code Map<String, User>} of all users stored locally with their user names as keys
 	 * @since Envoy Client v0.2-alpha
 	 */
 	public Map<String, User> getUsers() { return users; }
@@ -311,7 +417,8 @@ public final class LocalDB implements EventListener {
 	 * @since Envoy Client v0.1-beta
 	 */
 	public <T extends Message> Optional<T> getMessage(long id) {
-		return (Optional<T>) chats.stream().map(Chat::getMessages).flatMap(List::stream).filter(m -> m.getID() == id).findAny();
+		return (Optional<T>) chats.stream().map(Chat::getMessages).flatMap(List::stream)
+			.filter(m -> m.getID() == id).findAny();
 	}
 
 	/**
@@ -321,11 +428,12 @@ public final class LocalDB implements EventListener {
 	 * @return an optional containing the chat
 	 * @since Envoy Client v0.1-beta
 	 */
-	public Optional<Chat> getChat(long recipientID) { return chats.stream().filter(c -> c.getRecipient().getID() == recipientID).findAny(); }
+	public Optional<Chat> getChat(long recipientID) {
+		return chats.stream().filter(c -> c.getRecipient().getID() == recipientID).findAny();
+	}
 
 	/**
-	 * @return all saved {@link Chat} objects that list the client user as the
-	 *         sender
+	 * @return all saved {@link Chat} objects that list the client user as the sender
 	 * @since Envoy Client v0.1-alpha
 	 **/
 	public ObservableList<Chat> getChats() { return chats; }
@@ -359,7 +467,9 @@ public final class LocalDB implements EventListener {
 	 * @return {@code true} if an {@link IDGenerator} is present
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public boolean hasIDGenerator() { return idGenerator != null; }
+	public boolean hasIDGenerator() {
+		return idGenerator != null;
+	}
 
 	/**
 	 * @return the cache map for messages and message status changes
diff --git a/client/src/main/java/envoy/client/data/Settings.java b/client/src/main/java/envoy/client/data/Settings.java
index 9b317cd..a3b4cca 100644
--- a/client/src/main/java/envoy/client/data/Settings.java
+++ b/client/src/main/java/envoy/client/data/Settings.java
@@ -5,16 +5,16 @@ import java.util.*;
 import java.util.logging.Level;
 import java.util.prefs.Preferences;
 
-import envoy.client.event.EnvoyCloseEvent;
-import envoy.util.*;
-
 import dev.kske.eventbus.*;
 import dev.kske.eventbus.EventListener;
 
+import envoy.util.*;
+
+import envoy.client.event.EnvoyCloseEvent;
+
 /**
- * Manages all application settings, which are different objects that can be
- * changed during runtime and serialized them by using either the file system or
- * the {@link Preferences} API.
+ * Manages all application settings, which are different objects that can be changed during runtime
+ * and serialized them by using either the file system or the {@link Preferences} API.
  *
  * @author Leon Hofmeister
  * @author Maximilian K&auml;fer
@@ -29,7 +29,8 @@ public final class Settings implements EventListener {
 	/**
 	 * Settings are stored in this file.
 	 */
-	private static final File settingsFile = new File(ClientConfig.getInstance().getHomeDirectory(), "settings.ser");
+	private static final File settingsFile =
+		new File(ClientConfig.getInstance().getHomeDirectory(), "settings.ser");
 
 	/**
 	 * Singleton instance of this class.
@@ -37,8 +38,8 @@ public final class Settings implements EventListener {
 	private static Settings settings = new Settings();
 
 	/**
-	 * The way to instantiate the settings. Is set to private to deny other
-	 * instances of that object.
+	 * The way to instantiate the settings. Is set to private to deny other instances of that
+	 * object.
 	 *
 	 * @since Envoy Client v0.2-alpha
 	 */
@@ -68,7 +69,7 @@ public final class Settings implements EventListener {
 	 * @throws IOException if an error occurs while saving the themes
 	 * @since Envoy Client v0.2-alpha
 	 */
-	@Event(eventType = EnvoyCloseEvent.class, priority = 900)
+	@Event(eventType = EnvoyCloseEvent.class)
 	private void save() {
 		EnvoyLog.getLogger(Settings.class).log(Level.INFO, "Saving settings...");
 
@@ -76,20 +77,27 @@ public final class Settings implements EventListener {
 		try {
 			SerializationUtils.write(settingsFile, items);
 		} catch (final IOException e) {
-			EnvoyLog.getLogger(Settings.class).log(Level.SEVERE, "Unable to save settings file: ", e);
+			EnvoyLog.getLogger(Settings.class).log(Level.SEVERE, "Unable to save settings file: ",
+				e);
 		}
 	}
 
 	private void supplementDefaults() {
-		items.putIfAbsent("enterToSend", new SettingsItem<>(true, "Enter to send", "Sends a message by pressing the enter key."));
-		items.putIfAbsent("hideOnClose", new SettingsItem<>(false, "Hide on close", "Hides the chat window when it is closed."));
-		items.putIfAbsent("currentTheme", new SettingsItem<>("dark", "Current Theme Name", "The name of the currently selected theme."));
+		items.putIfAbsent("enterToSend", new SettingsItem<>(true, "Enter to send",
+			"Sends a message by pressing the enter key."));
+		items.putIfAbsent("hideOnClose",
+			new SettingsItem<>(false, "Hide on close", "Hides the chat window when it is closed."));
+		items.putIfAbsent("currentTheme", new SettingsItem<>("dark", "Current Theme Name",
+			"The name of the currently selected theme."));
 		items.putIfAbsent("downloadLocation",
-				new SettingsItem<>(new File(System.getProperty("user.home") + "/Downloads/"), "Download location",
-						"The location where files will be saved to"));
-		items.putIfAbsent("autoSaveDownloads", new SettingsItem<>(false, "Save without asking?", "Should downloads be saved without asking?"));
+			new SettingsItem<>(new File(System.getProperty("user.home") + "/Downloads/"),
+				"Download location",
+				"The location where files will be saved to"));
+		items.putIfAbsent("autoSaveDownloads", new SettingsItem<>(false, "Save without asking?",
+			"Should downloads be saved without asking?"));
 		items.putIfAbsent("askForConfirmation",
-				new SettingsItem<>(true, "Ask for confirmation", "Will ask for confirmation before doing certain things"));
+			new SettingsItem<>(true, "Ask for confirmation",
+				"Will ask for confirmation before doing certain things"));
 	}
 
 	/**
@@ -104,7 +112,9 @@ public final class Settings implements EventListener {
 	 * @param themeName the name to set
 	 * @since Envoy Client v0.2-alpha
 	 */
-	public void setCurrentTheme(String themeName) { ((SettingsItem<String>) items.get("currentTheme")).set(themeName); }
+	public void setCurrentTheme(String themeName) {
+		((SettingsItem<String>) items.get("currentTheme")).set(themeName);
+	}
 
 	/**
 	 * @return true if the currently used theme is one of the default themes
@@ -116,9 +126,8 @@ public final class Settings implements EventListener {
 	}
 
 	/**
-	 * @return {@code true}, if pressing the {@code Enter} key suffices to send a
-	 *         message. Otherwise it has to be pressed in conjunction with the
-	 *         {@code Control} key.
+	 * @return {@code true}, if pressing the {@code Enter} key suffices to send a message. Otherwise
+	 *         it has to be pressed in conjunction with the {@code Control} key.
 	 * @since Envoy Client v0.2-alpha
 	 */
 	public Boolean isEnterToSend() { return (Boolean) items.get("enterToSend").get(); }
@@ -126,26 +135,27 @@ public final class Settings implements EventListener {
 	/**
 	 * Changes the keystrokes performed by the user to send a message.
 	 *
-	 * @param enterToSend If set to {@code true} a message can be sent by pressing
-	 *                    the {@code Enter} key. Otherwise it has to be pressed in
-	 *                    conjunction with the {@code Control} key.
+	 * @param enterToSend If set to {@code true} a message can be sent by pressing the {@code Enter}
+	 *                    key. Otherwise it has to be pressed in conjunction with the
+	 *                    {@code Control} key.
 	 * @since Envoy Client v0.2-alpha
 	 */
-	public void setEnterToSend(boolean enterToSend) { ((SettingsItem<Boolean>) items.get("enterToSend")).set(enterToSend); }
+	public void setEnterToSend(boolean enterToSend) {
+		((SettingsItem<Boolean>) items.get("enterToSend")).set(enterToSend);
+	}
 
 	/**
-	 * @return whether Envoy will prompt a dialogue before saving an
-	 *         {@link envoy.data.Attachment}
+	 * @return whether Envoy will prompt a dialogue before saving an {@link envoy.data.Attachment}
 	 * @since Envoy Client v0.2-beta
 	 */
-	public Boolean isDownloadSavedWithoutAsking() { return (Boolean) items.get("autoSaveDownloads").get(); }
+	public Boolean isDownloadSavedWithoutAsking() {
+		return (Boolean) items.get("autoSaveDownloads").get();
+	}
 
 	/**
-	 * Sets whether Envoy will prompt a dialogue before saving an
-	 * {@link envoy.data.Attachment}.
+	 * Sets whether Envoy will prompt a dialogue before saving an {@link envoy.data.Attachment}.
 	 *
-	 * @param autosaveDownload whether a download should be saved without asking
-	 *                         before
+	 * @param autosaveDownload whether a download should be saved without asking before
 	 * @since Envoy Client v0.2-beta
 	 */
 	public void setDownloadSavedWithoutAsking(boolean autosaveDownload) {
@@ -164,7 +174,9 @@ public final class Settings implements EventListener {
 	 * @param downloadLocation the path to set
 	 * @since Envoy Client v0.2-beta
 	 */
-	public void setDownloadLocation(File downloadLocation) { ((SettingsItem<File>) items.get("downloadLocation")).set(downloadLocation); }
+	public void setDownloadLocation(File downloadLocation) {
+		((SettingsItem<File>) items.get("downloadLocation")).set(downloadLocation);
+	}
 
 	/**
 	 * @return the current on close mode.
@@ -178,21 +190,24 @@ public final class Settings implements EventListener {
 	 * @param hideOnClose whether the application should be minimized on close
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public void setHideOnClose(boolean hideOnClose) { ((SettingsItem<Boolean>) items.get("hideOnClose")).set(hideOnClose); }
+	public void setHideOnClose(boolean hideOnClose) {
+		((SettingsItem<Boolean>) items.get("hideOnClose")).set(hideOnClose);
+	}
 
 	/**
-	 * @return whether a confirmation dialog should be displayed before certain
-	 *         actions
+	 * @return whether a confirmation dialog should be displayed before certain actions
 	 * @since Envoy Client v0.2-alpha
 	 */
-	public Boolean isAskForConfirmation() { return (Boolean) items.get("askForConfirmation").get(); }
+	public Boolean isAskForConfirmation() {
+		return (Boolean) items.get("askForConfirmation").get();
+	}
 
 	/**
-	 * Changes the behavior of calling certain functionality by displaying a
-	 * confirmation dialog before executing it.
+	 * Changes the behavior of calling certain functionality by displaying a confirmation dialog
+	 * before executing it.
 	 *
-	 * @param askForConfirmation whether confirmation dialogs should be displayed
-	 *                           before certain actions
+	 * @param askForConfirmation whether confirmation dialogs should be displayed before certain
+	 *                           actions
 	 * @since Envoy Client v0.2-alpha
 	 */
 	public void setAskForConfirmation(boolean askForConfirmation) {
diff --git a/client/src/main/java/envoy/client/data/SettingsItem.java b/client/src/main/java/envoy/client/data/SettingsItem.java
index 3837071..590f965 100644
--- a/client/src/main/java/envoy/client/data/SettingsItem.java
+++ b/client/src/main/java/envoy/client/data/SettingsItem.java
@@ -6,8 +6,7 @@ import java.util.function.Consumer;
 import javax.swing.JComponent;
 
 /**
- * Encapsulates a persistent value that is directly or indirectly mutable by the
- * user.
+ * Encapsulates a persistent value that is directly or indirectly mutable by the user.
  *
  * @param <T> the type of this {@link SettingsItem}'s value
  * @author Kai S. K. Engelbart
@@ -23,9 +22,8 @@ public final class SettingsItem<T> implements Serializable {
 	private static final long serialVersionUID = 1L;
 
 	/**
-	 * Initializes a {@link SettingsItem}. The default value's class will be mapped
-	 * to a {@link JComponent} that can be used to display this {@link SettingsItem}
-	 * to the user.
+	 * Initializes a {@link SettingsItem}. The default value's class will be mapped to a
+	 * {@link JComponent} that can be used to display this {@link SettingsItem} to the user.
 	 *
 	 * @param value            the default value
 	 * @param userFriendlyName the user friendly name (short)
@@ -42,17 +40,20 @@ public final class SettingsItem<T> implements Serializable {
 	 * @return the value
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public T get() { return value; }
+	public T get() {
+		return value;
+	}
 
 	/**
-	 * Changes the value of this {@link SettingsItem}. If a {@code ChangeHandler} if
-	 * defined, it will be invoked with this value.
+	 * Changes the value of this {@link SettingsItem}. If a {@code ChangeHandler} if defined, it
+	 * will be invoked with this value.
 	 *
 	 * @param value the value to set
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public void set(T value) {
-		if (changeHandler != null && value != this.value) changeHandler.accept(value);
+		if (changeHandler != null && value != this.value)
+			changeHandler.accept(value);
 		this.value = value;
 	}
 
@@ -66,7 +67,9 @@ public final class SettingsItem<T> implements Serializable {
 	 * @param userFriendlyName the userFriendlyName to set
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public void setUserFriendlyName(String userFriendlyName) { this.userFriendlyName = userFriendlyName; }
+	public void setUserFriendlyName(String userFriendlyName) {
+		this.userFriendlyName = userFriendlyName;
+	}
 
 	/**
 	 * @return the description
@@ -81,9 +84,8 @@ public final class SettingsItem<T> implements Serializable {
 	public void setDescription(String description) { this.description = description; }
 
 	/**
-	 * Sets a {@code ChangeHandler} for this {@link SettingsItem}. It will be
-	 * invoked with the current value once during the registration and every time
-	 * when the value changes.
+	 * Sets a {@code ChangeHandler} for this {@link SettingsItem}. It will be invoked with the
+	 * current value once during the registration and every time when the value changes.
 	 *
 	 * @param changeHandler the changeHandler to set
 	 * @since Envoy Client v0.3-alpha
diff --git a/client/src/main/java/envoy/client/data/audio/AudioPlayer.java b/client/src/main/java/envoy/client/data/audio/AudioPlayer.java
index ec0440d..854f6bb 100644
--- a/client/src/main/java/envoy/client/data/audio/AudioPlayer.java
+++ b/client/src/main/java/envoy/client/data/audio/AudioPlayer.java
@@ -22,7 +22,9 @@ public final class AudioPlayer {
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
-	public AudioPlayer() { this(AudioRecorder.DEFAULT_AUDIO_FORMAT); }
+	public AudioPlayer() {
+		this(AudioRecorder.DEFAULT_AUDIO_FORMAT);
+	}
 
 	/**
 	 * Initializes the player with a given audio format.
diff --git a/client/src/main/java/envoy/client/data/audio/AudioRecorder.java b/client/src/main/java/envoy/client/data/audio/AudioRecorder.java
index 38475ab..37c3be2 100644
--- a/client/src/main/java/envoy/client/data/audio/AudioRecorder.java
+++ b/client/src/main/java/envoy/client/data/audio/AudioRecorder.java
@@ -20,7 +20,8 @@ public final class AudioRecorder {
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
-	public static final AudioFormat DEFAULT_AUDIO_FORMAT = new AudioFormat(16000, 16, 1, true, false);
+	public static final AudioFormat DEFAULT_AUDIO_FORMAT =
+		new AudioFormat(16000, 16, 1, true, false);
 
 	/**
 	 * The format in which audio files will be saved.
@@ -38,7 +39,9 @@ public final class AudioRecorder {
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
-	public AudioRecorder() { this(DEFAULT_AUDIO_FORMAT); }
+	public AudioRecorder() {
+		this(DEFAULT_AUDIO_FORMAT);
+	}
 
 	/**
 	 * Initializes the recorder with a given audio format.
diff --git a/client/src/main/java/envoy/client/data/audio/package-info.java b/client/src/main/java/envoy/client/data/audio/package-info.java
index 5e80e64..569abd9 100644
--- a/client/src/main/java/envoy/client/data/audio/package-info.java
+++ b/client/src/main/java/envoy/client/data/audio/package-info.java
@@ -1,6 +1,6 @@
 /**
  * Contains classes related to recording and playing back audio clips.
- * 
+ *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
  */
diff --git a/client/src/main/java/envoy/client/data/commands/Callable.java b/client/src/main/java/envoy/client/data/commands/Callable.java
index cd8c146..3e7285e 100644
--- a/client/src/main/java/envoy/client/data/commands/Callable.java
+++ b/client/src/main/java/envoy/client/data/commands/Callable.java
@@ -3,8 +3,7 @@ package envoy.client.data.commands;
 import java.util.List;
 
 /**
- * This interface defines an action that should be performed when a system
- * command gets called.
+ * This interface defines an action that should be performed when a system command gets called.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.2-beta
@@ -12,11 +11,9 @@ import java.util.List;
 public interface Callable {
 
 	/**
-	 * Performs the instance specific action when a {@link SystemCommand} has been
-	 * called.
+	 * Performs the instance specific action when a {@link SystemCommand} has been called.
 	 *
-	 * @param arguments the arguments that should be passed to the
-	 *                  {@link SystemCommand}
+	 * @param arguments the arguments that should be passed to the {@link SystemCommand}
 	 * @since Envoy Client v0.2-beta
 	 */
 	void call(List<String> arguments);
diff --git a/client/src/main/java/envoy/client/data/commands/SystemCommand.java b/client/src/main/java/envoy/client/data/commands/SystemCommand.java
index 7a788dd..66ba0de 100644
--- a/client/src/main/java/envoy/client/data/commands/SystemCommand.java
+++ b/client/src/main/java/envoy/client/data/commands/SystemCommand.java
@@ -4,15 +4,12 @@ import java.util.*;
 import java.util.function.Consumer;
 
 /**
- * This class is the base class of all {@code SystemCommands} and contains an
- * action and a number of arguments that should be used as input for this
- * function.
- * No {@code SystemCommand} can return anything.
- * Every {@code SystemCommand} must have as argument type {@code List<String>}
- * so that the words following the indicator String can be used as input of the
- * function. This approach has one limitation:<br>
- * <b>Order matters!</b> Changing the order of arguments will likely result in
- * unexpected behavior.
+ * This class is the base class of all {@code SystemCommands} and contains an action and a number of
+ * arguments that should be used as input for this function. No {@code SystemCommand} can return
+ * anything. Every {@code SystemCommand} must have as argument type {@code List<String>} so that the
+ * words following the indicator String can be used as input of the function. This approach has one
+ * limitation:<br>
+ * <b>Order matters!</b> Changing the order of arguments will likely result in unexpected behavior.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.2-beta
@@ -28,8 +25,8 @@ public final class SystemCommand implements Callable {
 
 	/**
 	 * This function takes a {@code List<String>} as argument because automatically
-	 * {@code SystemCommand#numberOfArguments} words following the necessary command
-	 * will be put into this list.
+	 * {@code SystemCommand#numberOfArguments} words following the necessary command will be put
+	 * into this list.
 	 *
 	 * @see String#split(String)
 	 */
@@ -48,7 +45,8 @@ public final class SystemCommand implements Callable {
 	 * @param description       the description of this {@code SystemCommand}
 	 * @since Envoy Client v0.2-beta
 	 */
-	public SystemCommand(Consumer<List<String>> action, int numberOfArguments, List<String> defaults, String description) {
+	public SystemCommand(Consumer<List<String>> action, int numberOfArguments,
+		List<String> defaults, String description) {
 		this.numberOfArguments	= numberOfArguments;
 		this.action				= action;
 		this.defaults			= defaults == null ? new ArrayList<>() : defaults;
@@ -92,20 +90,27 @@ public final class SystemCommand implements Callable {
 	public List<String> getDefaults() { return defaults; }
 
 	@Override
-	public int hashCode() { return Objects.hash(action); }
+	public int hashCode() {
+		return Objects.hash(action);
+	}
 
 	@Override
 	public boolean equals(Object obj) {
-		if (this == obj) return true;
-		if (obj == null) return false;
-		if (getClass() != obj.getClass()) return false;
+		if (this == obj)
+			return true;
+		if (obj == null)
+			return false;
+		if (getClass() != obj.getClass())
+			return false;
 		final var other = (SystemCommand) obj;
 		return Objects.equals(action, other.action);
 	}
 
 	@Override
 	public String toString() {
-		return "SystemCommand [relevance=" + relevance + ", numberOfArguments=" + numberOfArguments + ", "
-				+ (description != null ? "description=" + description + ", " : "") + (defaults != null ? "defaults=" + defaults : "") + "]";
+		return "SystemCommand [relevance=" + relevance + ", numberOfArguments=" + numberOfArguments
+			+ ", "
+			+ (description != null ? "description=" + description + ", " : "")
+			+ (defaults != null ? "defaults=" + defaults : "") + "]";
 	}
 }
diff --git a/client/src/main/java/envoy/client/data/commands/SystemCommandBuilder.java b/client/src/main/java/envoy/client/data/commands/SystemCommandBuilder.java
index 0768b5f..eb11c3d 100644
--- a/client/src/main/java/envoy/client/data/commands/SystemCommandBuilder.java
+++ b/client/src/main/java/envoy/client/data/commands/SystemCommandBuilder.java
@@ -20,18 +20,21 @@ public final class SystemCommandBuilder {
 	private final SystemCommandMap commandsMap;
 
 	/**
-	 * Creates a new {@code SystemCommandsBuilder} without underlying
-	 * {@link SystemCommandMap}.
+	 * Creates a new {@code SystemCommandsBuilder} without underlying {@link SystemCommandMap}.
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public SystemCommandBuilder() { this(null); }
+	public SystemCommandBuilder() {
+		this(null);
+	}
 
 	/**
 	 * @param commandsMap the map to use when calling build (optional)
 	 * @since Envoy Client v0.2-beta
 	 */
-	public SystemCommandBuilder(SystemCommandMap commandsMap) { this.commandsMap = commandsMap; }
+	public SystemCommandBuilder(SystemCommandMap commandsMap) {
+		this.commandsMap = commandsMap;
+	}
 
 	/**
 	 * @param numberOfArguments the numberOfArguments to set
@@ -104,12 +107,14 @@ public final class SystemCommandBuilder {
 	 * @return the built {@code SystemCommand}
 	 * @since Envoy Client v0.2-beta
 	 */
-	public SystemCommand build() { return build(true); }
+	public SystemCommand build() {
+		return build(true);
+	}
 
 	/**
 	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
-	 * {@code SystemCommand#numberOfArguments} will be set to 0, regardless of the
-	 * previous value.<br>
+	 * {@code SystemCommand#numberOfArguments} will be set to 0, regardless of the previous
+	 * value.<br>
 	 * At the end, this {@code SystemCommandBuilder} will be reset.
 	 *
 	 * @return the built {@code SystemCommand}
@@ -122,8 +127,8 @@ public final class SystemCommandBuilder {
 
 	/**
 	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
-	 * {@code SystemCommand#numberOfArguments} will be set to use the rest of the
-	 * string as argument, regardless of the previous value.<br>
+	 * {@code SystemCommand#numberOfArguments} will be set to use the rest of the string as
+	 * argument, regardless of the previous value.<br>
 	 * At the end, this {@code SystemCommandBuilder} will be reset.
 	 *
 	 * @return the built {@code SystemCommand}
@@ -136,27 +141,25 @@ public final class SystemCommandBuilder {
 
 	/**
 	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
-	 * Automatically adds the built object to the given map.
-	 * At the end, this {@code SystemCommandBuilder} <b>can</b> be reset but must
-	 * not be.
+	 * Automatically adds the built object to the given map. At the end, this
+	 * {@code SystemCommandBuilder} <b>can</b> be reset but must not be.
 	 *
-	 * @param reset whether this {@code SystemCommandBuilder} should be reset
-	 *              afterwards.<br>
-	 *              This can be useful if another command wants to execute something
-	 *              similar
+	 * @param reset whether this {@code SystemCommandBuilder} should be reset afterwards.<br>
+	 *              This can be useful if another command wants to execute something similar
 	 * @return the built {@code SystemCommand}
 	 * @since Envoy Client v0.2-beta
 	 */
 	public SystemCommand build(boolean reset) {
 		final var sc = new SystemCommand(action, numberOfArguments, defaults, description);
 		sc.setRelevance(relevance);
-		if (reset) reset();
+		if (reset)
+			reset();
 		return sc;
 	}
 
 	/**
-	 * Builds a {@code SystemCommand} based upon the previously entered data.
-	 * Automatically adds the built object to the given map.
+	 * Builds a {@code SystemCommand} based upon the previously entered data. Automatically adds the
+	 * built object to the given map.
 	 *
 	 * @param command the command under which to store the SystemCommand in the
 	 *                {@link SystemCommandMap}
@@ -164,13 +167,14 @@ public final class SystemCommandBuilder {
 	 * @throws NullPointerException if no map has been assigned to this builder
 	 * @since Envoy Client v0.2-beta
 	 */
-	public SystemCommand build(String command) { return build(command, true); }
+	public SystemCommand build(String command) {
+		return build(command, true);
+	}
 
 	/**
 	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
-	 * Automatically adds the built object to the given map.
-	 * {@code SystemCommand#numberOfArguments} will be set to 0, regardless of the
-	 * previous value.<br>
+	 * Automatically adds the built object to the given map. {@code SystemCommand#numberOfArguments}
+	 * will be set to 0, regardless of the previous value.<br>
 	 * At the end, this {@code SystemCommandBuilder} will be reset.
 	 *
 	 * @param command the command under which to store the SystemCommand in the
@@ -186,9 +190,8 @@ public final class SystemCommandBuilder {
 
 	/**
 	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
-	 * Automatically adds the built object to the given map.
-	 * {@code SystemCommand#numberOfArguments} will be set to use the rest of the
-	 * string as argument, regardless of the previous value.<br>
+	 * Automatically adds the built object to the given map. {@code SystemCommand#numberOfArguments}
+	 * will be set to use the rest of the string as argument, regardless of the previous value.<br>
 	 * At the end, this {@code SystemCommandBuilder} will be reset.
 	 *
 	 * @param command the command under which to store the SystemCommand in the
@@ -204,17 +207,13 @@ public final class SystemCommandBuilder {
 
 	/**
 	 * Builds a {@code SystemCommand} based upon the previously entered data.<br>
-	 * Automatically adds the built object to the given map.
-	 * At the end, this {@code SystemCommandBuilder} <b>can</b> be reset but must
-	 * not be.
+	 * Automatically adds the built object to the given map. At the end, this
+	 * {@code SystemCommandBuilder} <b>can</b> be reset but must not be.
 	 *
 	 * @param command the command under which to store the SystemCommand in the
 	 *                {@link SystemCommandMap}
-	 * @param reset   whether this {@code SystemCommandBuilder} should be reset
-	 *                afterwards.<br>
-	 *                This can be useful if another command wants to execute
-	 *                something
-	 *                similar
+	 * @param reset   whether this {@code SystemCommandBuilder} should be reset afterwards.<br>
+	 *                This can be useful if another command wants to execute something similar
 	 * @return the built {@code SystemCommand}
 	 * @throws NullPointerException if no map has been assigned to this builder
 	 * @since Envoy Client v0.2-beta
@@ -222,9 +221,12 @@ public final class SystemCommandBuilder {
 	public SystemCommand build(String command, boolean reset) {
 		final var sc = new SystemCommand(action, numberOfArguments, defaults, description);
 		sc.setRelevance(relevance);
-		if (commandsMap != null) commandsMap.add(command, sc);
-		else throw new NullPointerException("No map in SystemCommandsBuilder present");
-		if (reset) reset();
+		if (commandsMap != null)
+			commandsMap.add(command, sc);
+		else
+			throw new NullPointerException("No map in SystemCommandsBuilder present");
+		if (reset)
+			reset();
 		return sc;
 	}
 }
diff --git a/client/src/main/java/envoy/client/data/commands/SystemCommandMap.java b/client/src/main/java/envoy/client/data/commands/SystemCommandMap.java
index 831de0d..1d2f635 100644
--- a/client/src/main/java/envoy/client/data/commands/SystemCommandMap.java
+++ b/client/src/main/java/envoy/client/data/commands/SystemCommandMap.java
@@ -14,11 +14,9 @@ import javafx.scene.control.Alert.AlertType;
 import envoy.util.EnvoyLog;
 
 /**
- * Stores all {@link SystemCommand}s used.
- * SystemCommands can be called using an activator char and the text that needs
- * to be present behind the activator.
- * Additionally offers the option to request recommendations for a partial input
- * String.
+ * Stores all {@link SystemCommand}s used. SystemCommands can be called using an activator char and
+ * the text that needs to be present behind the activator. Additionally offers the option to request
+ * recommendations for a partial input String.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.2-beta
@@ -27,96 +25,100 @@ public final class SystemCommandMap {
 
 	private final Character						activator;
 	private final Map<String, SystemCommand>	systemCommands	= new HashMap<>();
-	private final Pattern						commandPattern	= Pattern.compile("^[a-zA-Z0-9_:!/\\(\\)\\?\\.\\,\\;\\-]+$");
+	private final Pattern						commandPattern	=
+		Pattern.compile("^[a-zA-Z0-9_:!/\\(\\)\\?\\.\\,\\;\\-]+$");
 
 	private static final Logger logger = EnvoyLog.getLogger(SystemCommandMap.class);
 
 	/**
-	 * Creates a new {@code SystemCommandMap} with the given char as activator.
-	 * If this Character is null, any text used as input will be treated as a system
-	 * command.
+	 * Creates a new {@code SystemCommandMap} with the given char as activator. If this Character is
+	 * null, any text used as input will be treated as a system command.
 	 *
 	 * @param activator the char to use as activator for commands
 	 * @since Envoy Client v0.3-beta
 	 */
-	public SystemCommandMap(Character activator) { this.activator = activator; }
+	public SystemCommandMap(Character activator) {
+		this.activator = activator;
+	}
 
 	/**
 	 * Creates a new {@code SystemCommandMap} with '/' as activator.
 	 *
 	 * @since Envoy Client v0.3-beta
 	 */
-	public SystemCommandMap() { activator = '/'; }
+	public SystemCommandMap() {
+		activator = '/';
+	}
 
 	/**
 	 * Adds a new command to the map if the command name is valid.
 	 *
-	 * @param command       the input string to execute the
-	 *                      given action
-	 * @param systemCommand the command to add - can be built using
-	 *                      {@link SystemCommandBuilder}
+	 * @param command       the input string to execute the given action
+	 * @param systemCommand the command to add - can be built using {@link SystemCommandBuilder}
 	 * @see SystemCommandMap#isValidKey(String)
 	 * @since Envoy Client v0.2-beta
 	 */
 	public void add(String command, SystemCommand systemCommand) {
-		if (isValidKey(command)) systemCommands.put(command.toLowerCase(), systemCommand);
+		if (isValidKey(command))
+			systemCommands.put(command.toLowerCase(), systemCommand);
 	}
 
 	/**
-	 * This method checks if the input String is a key in the map and returns the
-	 * wrapped System command if present.
+	 * This method checks if the input String is a key in the map and returns the wrapped System
+	 * command if present.
 	 * <p>
 	 * Usage example:<br>
 	 * {@code SystemCommandMap systemCommands = new SystemCommandMap('*');}<br>
-	 * {@code systemCommands.add("example", new SystemCommand(text -> {}, 1, null,
-	 * ""));}<br>
+	 * {@code systemCommands.add("example", new SystemCommand(text -> {}, 1, null, ""));}<br>
 	 * {@code ....}<br>
 	 * user input: {@code "*example xyz ..."}<br>
 	 * {@code systemCommands.get("example xyz ...")} or
-	 * {@code systemCommands.get("*example xyz ...")}
-	 * result: {@code Optional<SystemCommand>.get() != null}
+	 * {@code systemCommands.get("*example xyz ...")} result:
+	 * {@code Optional<SystemCommand>.get() != null}
 	 *
 	 * @param input the input string given by the user
 	 * @return the wrapped system command, if present
 	 * @since Envoy Client v0.2-beta
 	 */
-	public Optional<SystemCommand> get(String input) { return Optional.ofNullable(systemCommands.get(getCommand(input.toLowerCase()))); }
+	public Optional<SystemCommand> get(String input) {
+		return Optional.ofNullable(systemCommands.get(getCommand(input.toLowerCase())));
+	}
 
 	/**
-	 * This method ensures that the activator of a {@link SystemCommand} is
-	 * stripped.<br>
-	 * It only checks the word beginning from the first non-blank position in the
-	 * input.
-	 * It returns the command as (most likely) entered as key in the map for the
-	 * first word of the text.<br>
+	 * This method ensures that the activator of a {@link SystemCommand} is stripped.<br>
+	 * It only checks the word beginning from the first non-blank position in the input. It returns
+	 * the command as (most likely) entered as key in the map for the first word of the text.<br>
 	 * Activators in the middle of the word will be disregarded.
 	 *
 	 * @param raw the input
 	 * @return the command as entered in the map
 	 * @since Envoy Client v0.2-beta
-	 * @apiNote this method will (most likely) not return anything useful if
-	 *          whatever is entered after the activator is not a system command.
-	 *          Only exception: for recommendation purposes.
+	 * @apiNote this method will (most likely) not return anything useful if whatever is entered
+	 *          after the activator is not a system command. Only exception: for recommendation
+	 *          purposes.
 	 */
 	public String getCommand(String raw) {
 		final var trimmed = raw.stripLeading();
 
 		// Entering only the activator should not throw an error
-		if (trimmed.length() == 1 && activator != null && activator.equals(trimmed.charAt(0))) return "";
+		if (trimmed.length() == 1 && activator != null && activator.equals(trimmed.charAt(0)))
+			return "";
 		else {
 			final var index = trimmed.indexOf(' ');
-			return trimmed.substring(activator != null && activator.equals(trimmed.charAt(0)) ? 1 : 0, index < 1 ? trimmed.length() : index);
+			return trimmed.substring(
+				activator != null && activator.equals(trimmed.charAt(0)) ? 1 : 0,
+				index < 1 ? trimmed.length() : index);
 		}
 	}
 
 	/**
-	 * Examines whether a key can be put in the map and logs it with
-	 * {@code Level.WARNING} if that key violates API constrictions.<br>
+	 * Examines whether a key can be put in the map and logs it with {@code Level.WARNING} if that
+	 * key violates API constrictions.<br>
 	 * (allowed chars are <b>a-zA-Z0-9_:!/()?.,;-</b>)
 	 * <p>
-	 * The approach to not throw an exception was taken so that an ugly try-catch
-	 * block for every addition to the system commands map could be avoided, an
-	 * error that should only occur during implementation and not in production.
+	 * The approach to not throw an exception was taken so that an ugly try-catch block for every
+	 * addition to the system commands map could be avoided, an error that should only occur during
+	 * implementation and not in production.
 	 *
 	 * @param command the key to examine
 	 * @return whether this key can be used in the map
@@ -124,17 +126,18 @@ public final class SystemCommandMap {
 	 */
 	public boolean isValidKey(String command) {
 		final var valid = commandPattern.matcher(command).matches();
-		if (!valid) logger.log(Level.WARNING,
+		if (!valid)
+			logger.log(Level.WARNING,
 				"The command \"" + command
-						+ "\" is not valid. As it might cause problems when executed, it will not be entered into the map. Only the characters "
-						+ commandPattern + "are allowed");
+					+ "\" is not valid. As it might cause problems when executed, it will not be entered into the map. Only the characters "
+					+ commandPattern + "are allowed");
 		return valid;
 	}
 
 	/**
-	 * Takes a 'raw' string (the whole input) and checks if the activator is the
-	 * first visible character and then checks if a command is present after that
-	 * activator. If that is the case, it will be executed.
+	 * Takes a 'raw' string (the whole input) and checks if the activator is the first visible
+	 * character and then checks if a command is present after that activator. If that is the case,
+	 * it will be executed.
 	 *
 	 * @param raw the raw input string
 	 * @return whether a command could be found and successfully executed
@@ -144,24 +147,26 @@ public final class SystemCommandMap {
 
 		// possibly a command was detected and could be executed
 		final var	raw2			= raw.stripLeading();
-		final var	commandFound	= activator == null || raw2.startsWith(activator.toString()) ? executeAvailableCommand(raw2) : false;
+		final var	commandFound	= activator == null || raw2.startsWith(activator.toString())
+			? executeAvailableCommand(raw2)
+			: false;
 
 		// the command was executed successfully - no further checking needed
-		if (commandFound) logger.log(Level.FINE, "executed system command " + getCommand(raw2));
+		if (commandFound)
+			logger.log(Level.FINE, "executed system command " + getCommand(raw2));
 		return commandFound;
 	}
 
 	/**
 	 * Retrieves the recommendations based on the current input entered.<br>
-	 * The first word is used for the recommendations and
-	 * it does not matter if the activator is at its beginning or not.<br>
+	 * The first word is used for the recommendations and it does not matter if the activator is at
+	 * its beginning or not.<br>
 	 * If recommendations are present, the given function will be executed on the
 	 * recommendations.<br>
 	 * Otherwise nothing will be done.<br>
 	 *
 	 * @param input  the input string
-	 * @param action the action that should be taken for the recommendations, if any
-	 *               are present
+	 * @param action the action that should be taken for the recommendations, if any are present
 	 * @since Envoy Client v0.2-beta
 	 */
 	public void requestRecommendations(String input, Consumer<Set<String>> action) {
@@ -169,27 +174,28 @@ public final class SystemCommandMap {
 
 		// Get the expected commands
 		final var recommendations = recommendCommands(partialCommand);
-		if (recommendations.isEmpty()) return;
+		if (recommendations.isEmpty())
+			return;
 
 		// Execute the given action
-		else action.accept(recommendations);
+		else
+			action.accept(recommendations);
 	}
 
 	/**
-	 * This method checks if the input String is a key in the map and executes the
-	 * wrapped System command if present.
+	 * This method checks if the input String is a key in the map and executes the wrapped System
+	 * command if present.
 	 * <p>
 	 * Usage example:<br>
 	 * {@code SystemCommandMap systemCommands = new SystemCommandMap('*');}<br>
 	 * {@code Button button = new Button();}<br>
-	 * {@code systemCommands.add("example", new SystemCommand(text ->
-	 * {button.setText(text.get(0))}, 1, null,
-	 * ""));}<br>
+	 * {@code systemCommands.add("example", new SystemCommand(text -> {button.setText(text.get(0))},
+	 * 1, null, ""));}<br>
 	 * {@code ....}<br>
 	 * user input: {@code "*example xyz ..."}<br>
 	 * {@code systemCommands.executeIfPresent("example xyz ...")} or
-	 * {@code systemCommands.executeIfPresent("*example xyz ...")}
-	 * result: {@code button.getText()=="xyz"}
+	 * {@code systemCommands.executeIfPresent("*example xyz ...")} result:
+	 * {@code button.getText()=="xyz"}
 	 *
 	 * @param input the input string given by the user
 	 * @return whether a command could be found and successfully executed
@@ -211,9 +217,9 @@ public final class SystemCommandMap {
 				systemCommand.call(arguments);
 			} catch (final NumberFormatException e) {
 				logger.log(Level.INFO,
-						String.format(
-								"System command %s could not be performed correctly because the user is a dumbass and could not write a parseable number.",
-								command));
+					String.format(
+						"System command %s could not be performed correctly because the user is a dumbass and could not write a parseable number.",
+						command));
 				Platform.runLater(() -> {
 					final var alert = new Alert(AlertType.ERROR);
 					alert.setContentText("Please enter a readable number as argument.");
@@ -224,7 +230,8 @@ public final class SystemCommandMap {
 				logger.log(Level.WARNING, "System command " + command + " threw an exception: ", e);
 				Platform.runLater(() -> {
 					final var alert = new Alert(AlertType.ERROR);
-					alert.setContentText("Could not execute system command: Internal error. Please insult the responsible programmer.");
+					alert.setContentText(
+						"Could not execute system command: Internal error. Please insult the responsible programmer.");
 					alert.showAndWait();
 				});
 				commandExecuted.set(false);
@@ -245,7 +252,8 @@ public final class SystemCommandMap {
 
 		// no more arguments follow after the command (e.g. text = "/DABR")
 		final var indexOfSpace = input.indexOf(" ");
-		if (indexOfSpace < 0) return supplementDefaults(new String[] {}, systemCommand);
+		if (indexOfSpace < 0)
+			return supplementDefaults(new String[] {}, systemCommand);
 
 		// the arguments behind a system command
 		final var	remainingString		= input.substring(indexOfSpace + 1);
@@ -253,15 +261,17 @@ public final class SystemCommandMap {
 
 		// splitting those arguments and supplying default values
 		final var	textArguments		= remainingString.split(" ", -1);
-		final var	originalArguments	= numberOfArguments >= 0 ? Arrays.copyOfRange(textArguments, 0, numberOfArguments) : textArguments;
+		final var	originalArguments	=
+			numberOfArguments >= 0 ? Arrays.copyOfRange(textArguments, 0, numberOfArguments)
+				: textArguments;
 		final var	arguments			= supplementDefaults(originalArguments, systemCommand);
 		return arguments;
 	}
 
 	/**
 	 * Recommends commands based upon the currently entered input.<br>
-	 * In the current implementation, all that gets checked is whether a key
-	 * contains this input. This might be updated later on.
+	 * In the current implementation, all that gets checked is whether a key contains this input.
+	 * This might be updated later on.
 	 *
 	 * @param partialCommand the partially entered command
 	 * @return a set of all commands that match this input
@@ -274,36 +284,41 @@ public final class SystemCommandMap {
 		return systemCommands.keySet()
 			.stream()
 			.filter(command -> command.contains(partialCommand))
-			.sorted((command1, command2) -> Integer.compare(systemCommands.get(command1).getRelevance(), systemCommands.get(command2).getRelevance()))
+			.sorted(
+				(command1, command2) -> Integer.compare(systemCommands.get(command1).getRelevance(),
+					systemCommands.get(command2).getRelevance()))
 			.collect(Collectors.toSet());
 	}
 
 	/**
-	 * Supplies the default values for arguments if none are present in the text for
-	 * any argument. <br>
+	 * Supplies the default values for arguments if none are present in the text for any argument.
+	 * <br>
 	 *
 	 * @param textArguments the arguments that were parsed from the text
 	 * @param toEvaluate    the system command whose default values should be used
 	 * @return the final argument list
 	 * @since Envoy Client v0.2-beta
-	 * @apiNote this method will insert an empty String if the size of the list
-	 *          given to the {@code SystemCommand} is smaller than its argument
-	 *          counter and no more text arguments could be found.
+	 * @apiNote this method will insert an empty String if the size of the list given to the
+	 *          {@code SystemCommand} is smaller than its argument counter and no more text
+	 *          arguments could be found.
 	 */
 	private List<String> supplementDefaults(String[] textArguments, SystemCommand toEvaluate) {
 		final var			defaults			= toEvaluate.getDefaults();
 		final var			numberOfArguments	= toEvaluate.getNumberOfArguments();
 		final List<String>	result				= new ArrayList<>();
 
-		if (toEvaluate.getNumberOfArguments() > 0) for (var index = 0; index < numberOfArguments; index++) {
-			String textArg = null;
-			if (index < textArguments.length) textArg = textArguments[index];
+		if (toEvaluate.getNumberOfArguments() > 0)
+			for (var index = 0; index < numberOfArguments; index++) {
+				String textArg = null;
+				if (index < textArguments.length)
+					textArg = textArguments[index];
 
-			// Set the argument at position index to the current argument of the text, if it
-			// is present. Otherwise the default for that argument will be taken if present.
-			// In the worst case, an empty String will be used.
-			result.add(!(textArg == null) && !textArg.isBlank() ? textArg : index < defaults.size() ? defaults.get(index) : "");
-		}
+				// Set the argument at position index to the current argument of the text, if it
+				// is present. Otherwise the default for that argument will be taken if present.
+				// In the worst case, an empty String will be used.
+				result.add(!(textArg == null) && !textArg.isBlank() ? textArg
+					: index < defaults.size() ? defaults.get(index) : "");
+			}
 		return result;
 	}
 
diff --git a/client/src/main/java/envoy/client/data/shortcuts/EnvoyShortcutConfig.java b/client/src/main/java/envoy/client/data/shortcuts/EnvoyShortcutConfig.java
index 14a110c..44504e1 100644
--- a/client/src/main/java/envoy/client/data/shortcuts/EnvoyShortcutConfig.java
+++ b/client/src/main/java/envoy/client/data/shortcuts/EnvoyShortcutConfig.java
@@ -2,6 +2,8 @@ package envoy.client.data.shortcuts;
 
 import javafx.scene.input.*;
 
+import envoy.data.User.UserStatus;
+
 import envoy.client.data.Context;
 import envoy.client.helper.ShutdownHelper;
 import envoy.client.ui.SceneContext.SceneInfo;
@@ -28,17 +30,48 @@ public class EnvoyShortcutConfig {
 
 		// Add the option to exit with "Control" + "Q" or "Alt" + "F4" as offered by
 		// some desktop environments
-		instance.add(new KeyCodeCombination(KeyCode.Q, KeyCombination.CONTROL_DOWN), ShutdownHelper::exit);
+		instance.add(new KeyCodeCombination(KeyCode.Q, KeyCombination.CONTROL_DOWN),
+			ShutdownHelper::exit);
 
 		// Add the option to logout using "Control"+"Shift"+"L" if not in login scene
-		instance.addForNotExcluded(new KeyCodeCombination(KeyCode.L, KeyCombination.CONTROL_DOWN, KeyCombination.SHIFT_DOWN),
-				UserUtil::logout,
-				SceneInfo.LOGIN_SCENE);
+		instance.addForNotExcluded(
+			new KeyCodeCombination(KeyCode.L, KeyCombination.CONTROL_DOWN,
+				KeyCombination.SHIFT_DOWN),
+			UserUtil::logout,
+			SceneInfo.LOGIN_SCENE);
 
 		// Add option to open settings scene with "Control"+"S", if not in login scene
 		instance.addForNotExcluded(new KeyCodeCombination(KeyCode.S, KeyCombination.CONTROL_DOWN),
-				() -> Context.getInstance().getSceneContext().load(SceneInfo.SETTINGS_SCENE),
-				SceneInfo.SETTINGS_SCENE,
-				SceneInfo.LOGIN_SCENE);
+			() -> Context.getInstance().getSceneContext().load(SceneInfo.SETTINGS_SCENE),
+			SceneInfo.SETTINGS_SCENE,
+			SceneInfo.LOGIN_SCENE);
+
+		// Add option to change to status away
+		instance.addForNotExcluded(
+			new KeyCodeCombination(KeyCode.A, KeyCombination.CONTROL_DOWN,
+				KeyCombination.SHIFT_DOWN),
+			() -> UserUtil.changeStatus(UserStatus.AWAY),
+			SceneInfo.LOGIN_SCENE);
+
+		// Add option to change to status busy
+		instance.addForNotExcluded(
+			new KeyCodeCombination(KeyCode.B, KeyCombination.CONTROL_DOWN,
+				KeyCombination.SHIFT_DOWN),
+			() -> UserUtil.changeStatus(UserStatus.BUSY),
+			SceneInfo.LOGIN_SCENE);
+
+		// Add option to change to status offline
+		instance.addForNotExcluded(
+			new KeyCodeCombination(KeyCode.F, KeyCombination.CONTROL_DOWN,
+				KeyCombination.SHIFT_DOWN),
+			() -> UserUtil.changeStatus(UserStatus.OFFLINE),
+			SceneInfo.LOGIN_SCENE);
+
+		// Add option to change to status online
+		instance.addForNotExcluded(
+			new KeyCodeCombination(KeyCode.N, KeyCombination.CONTROL_DOWN,
+				KeyCombination.SHIFT_DOWN),
+			() -> UserUtil.changeStatus(UserStatus.ONLINE),
+			SceneInfo.LOGIN_SCENE);
 	}
 }
diff --git a/client/src/main/java/envoy/client/data/shortcuts/GlobalKeyShortcuts.java b/client/src/main/java/envoy/client/data/shortcuts/GlobalKeyShortcuts.java
index c3643ee..05ef3b7 100644
--- a/client/src/main/java/envoy/client/data/shortcuts/GlobalKeyShortcuts.java
+++ b/client/src/main/java/envoy/client/data/shortcuts/GlobalKeyShortcuts.java
@@ -14,7 +14,8 @@ import envoy.client.ui.SceneContext.SceneInfo;
  */
 public final class GlobalKeyShortcuts {
 
-	private final EnumMap<SceneInfo, Map<KeyCombination, Runnable>> shortcuts = new EnumMap<>(SceneInfo.class);
+	private final EnumMap<SceneInfo, Map<KeyCombination, Runnable>> shortcuts =
+		new EnumMap<>(SceneInfo.class);
 
 	private static GlobalKeyShortcuts instance = new GlobalKeyShortcuts();
 
@@ -36,16 +37,16 @@ public final class GlobalKeyShortcuts {
 	 * @param action the action to perform
 	 * @since Envoy Client v0.3-beta
 	 */
-	public void add(KeyCombination keys, Runnable action) { shortcuts.values().forEach(collection -> collection.put(keys, action)); }
+	public void add(KeyCombination keys, Runnable action) {
+		shortcuts.values().forEach(collection -> collection.put(keys, action));
+	}
 
 	/**
-	 * Adds the given keyboard shortcut and its action to all scenes that are not
-	 * part of exclude.
+	 * Adds the given keyboard shortcut and its action to all scenes that are not part of exclude.
 	 *
 	 * @param keys    the keys to press to perform the given action
 	 * @param action  the action to perform
-	 * @param exclude the scenes that should be excluded from receiving this
-	 *                keyboard shortcut
+	 * @param exclude the scenes that should be excluded from receiving this keyboard shortcut
 	 * @since Envoy Client v0.3-beta
 	 */
 	public void addForNotExcluded(KeyCombination keys, Runnable action, SceneInfo... exclude) {
@@ -53,10 +54,10 @@ public final class GlobalKeyShortcuts {
 		// Computing the remaining sceneInfos
 		final var	include	= new SceneInfo[SceneInfo.values().length - exclude.length];
 		int			index	= 0;
-		outer:
-		for (final var sceneInfo : SceneInfo.values()) {
+		outer: for (final var sceneInfo : SceneInfo.values()) {
 			for (final var excluded : exclude)
-				if (sceneInfo.equals(excluded)) continue outer;
+				if (sceneInfo.equals(excluded))
+					continue outer;
 			include[index++] = sceneInfo;
 		}
 
@@ -72,5 +73,7 @@ public final class GlobalKeyShortcuts {
 	 * @return all stored keyboard shortcuts for this scene
 	 * @since Envoy Client v0.3-beta
 	 */
-	public Map<KeyCombination, Runnable> getKeyboardShortcuts(SceneInfo sceneInfo) { return shortcuts.get(sceneInfo); }
+	public Map<KeyCombination, Runnable> getKeyboardShortcuts(SceneInfo sceneInfo) {
+		return shortcuts.get(sceneInfo);
+	}
 }
diff --git a/client/src/main/java/envoy/client/data/shortcuts/KeyboardMapping.java b/client/src/main/java/envoy/client/data/shortcuts/KeyboardMapping.java
index 4d56f8e..6666f61 100644
--- a/client/src/main/java/envoy/client/data/shortcuts/KeyboardMapping.java
+++ b/client/src/main/java/envoy/client/data/shortcuts/KeyboardMapping.java
@@ -7,10 +7,9 @@ import javafx.scene.input.KeyCombination;
 import envoy.client.ui.SceneContext;
 
 /**
- * Provides methods to set the keyboard shortcuts for a specific scene.
- * Should only be implemented by controllers of scenes so that these methods can
- * automatically be called inside {@link SceneContext} as soon
- * as the underlying FXML file has been loaded.
+ * Provides methods to set the keyboard shortcuts for a specific scene. Should only be implemented
+ * by controllers of scenes so that these methods can automatically be called inside
+ * {@link SceneContext} as soon as the underlying FXML file has been loaded.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.3-beta
diff --git a/client/src/main/java/envoy/client/event/ContactDisabled.java b/client/src/main/java/envoy/client/event/ContactDisabled.java
new file mode 100644
index 0000000..4b73a92
--- /dev/null
+++ b/client/src/main/java/envoy/client/event/ContactDisabled.java
@@ -0,0 +1,23 @@
+package envoy.client.event;
+
+import envoy.data.Contact;
+import envoy.event.Event;
+
+/**
+ * Signifies that the chat of a contact should be disabled.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public class ContactDisabled extends Event<Contact> {
+
+	private static final long serialVersionUID = 1L;
+
+	/**
+	 * @param contact the contact that should be disabled
+	 * @since Envoy Client v0.3-beta
+	 */
+	public ContactDisabled(Contact contact) {
+		super(contact);
+	}
+}
diff --git a/client/src/main/java/envoy/client/event/EnvoyCloseEvent.java b/client/src/main/java/envoy/client/event/EnvoyCloseEvent.java
index dfe15ec..c7266a8 100644
--- a/client/src/main/java/envoy/client/event/EnvoyCloseEvent.java
+++ b/client/src/main/java/envoy/client/event/EnvoyCloseEvent.java
@@ -3,9 +3,8 @@ package envoy.client.event;
 import envoy.event.Event.Valueless;
 
 /**
- * This event notifies various Envoy components of the application being about
- * to shut down. This allows the graceful closing of connections, persisting
- * local data etc.
+ * This event notifies various Envoy components of the application being about to shut down. This
+ * allows the graceful closing of connections, persisting local data etc.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.2-beta
diff --git a/client/src/main/java/envoy/client/event/MessageDeletion.java b/client/src/main/java/envoy/client/event/MessageDeletion.java
index e3f5ada..46a435a 100644
--- a/client/src/main/java/envoy/client/event/MessageDeletion.java
+++ b/client/src/main/java/envoy/client/event/MessageDeletion.java
@@ -16,5 +16,7 @@ public class MessageDeletion extends Event<Long> {
 	 * @param messageID the ID of the deleted message
 	 * @since Envoy Common v0.3-beta
 	 */
-	public MessageDeletion(long messageID) { super(messageID); }
+	public MessageDeletion(long messageID) {
+		super(messageID);
+	}
 }
diff --git a/client/src/main/java/envoy/client/event/OwnStatusChange.java b/client/src/main/java/envoy/client/event/OwnStatusChange.java
index 8962d6f..3c144ef 100644
--- a/client/src/main/java/envoy/client/event/OwnStatusChange.java
+++ b/client/src/main/java/envoy/client/event/OwnStatusChange.java
@@ -17,5 +17,7 @@ public class OwnStatusChange extends Event<UserStatus> {
 	 * @param value the new user status of the client user
 	 * @since Envoy Client v0.3-beta
 	 */
-	public OwnStatusChange(UserStatus value) { super(value); }
+	public OwnStatusChange(UserStatus value) {
+		super(value);
+	}
 }
diff --git a/client/src/main/java/envoy/client/helper/AlertHelper.java b/client/src/main/java/envoy/client/helper/AlertHelper.java
index 6b053f7..71c8cfb 100644
--- a/client/src/main/java/envoy/client/helper/AlertHelper.java
+++ b/client/src/main/java/envoy/client/helper/AlertHelper.java
@@ -15,20 +15,19 @@ public final class AlertHelper {
 	private AlertHelper() {}
 
 	/**
-	 * Asks for a confirmation dialog if {@link Settings#isAskForConfirmation()}
-	 * returns {@code true}.
-	 * Immediately executes the action if no dialog was requested or the dialog was
-	 * exited with a confirmation.
-	 * Does nothing if the dialog was closed without clicking on OK.
+	 * Asks for a confirmation dialog if {@link Settings#isAskForConfirmation()} returns
+	 * {@code true}. Immediately executes the action if no dialog was requested or the dialog was
+	 * exited with a confirmation. Does nothing if the dialog was closed without clicking on OK.
 	 *
-	 * @param alert  the (customized) alert to show. <strong>Should not be shown
-	 *               already</strong>
+	 * @param alert  the (customized) alert to show. <strong>Should not be shown already</strong>
 	 * @param action the action to perform in case of success
 	 * @since Envoy Client v0.2-beta
 	 */
 	public static void confirmAction(Alert alert, Runnable action) {
 		alert.setHeaderText("");
-		if (Settings.getInstance().isAskForConfirmation()) alert.showAndWait().filter(ButtonType.OK::equals).ifPresent(bu -> action.run());
-		else action.run();
+		if (Settings.getInstance().isAskForConfirmation())
+			alert.showAndWait().filter(ButtonType.OK::equals).ifPresent(bu -> action.run());
+		else
+			action.run();
 	}
 }
diff --git a/client/src/main/java/envoy/client/helper/ShutdownHelper.java b/client/src/main/java/envoy/client/helper/ShutdownHelper.java
index 0371f50..8997736 100644
--- a/client/src/main/java/envoy/client/helper/ShutdownHelper.java
+++ b/client/src/main/java/envoy/client/helper/ShutdownHelper.java
@@ -1,11 +1,11 @@
 package envoy.client.helper;
 
+import dev.kske.eventbus.EventBus;
+
 import envoy.client.data.*;
 import envoy.client.event.EnvoyCloseEvent;
 import envoy.client.ui.StatusTrayIcon;
 
-import dev.kske.eventbus.EventBus;
-
 /**
  * Simplifies shutdown actions.
  *
@@ -22,18 +22,21 @@ public final class ShutdownHelper {
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public static void exit() { exit(false); }
+	public static void exit() {
+		exit(false);
+	}
 
 	/**
-	 * Exits Envoy immediately if {@code force = true},
-	 * else it can exit or minimize Envoy, depending on the current state of
-	 * {@link Settings#isHideOnClose()} and {@link StatusTrayIcon#isSupported()}.
+	 * Exits Envoy immediately if {@code force = true}, else it can exit or minimize Envoy,
+	 * depending on the current state of {@link Settings#isHideOnClose()} and
+	 * {@link StatusTrayIcon#isSupported()}.
 	 *
 	 * @param force whether to close in any case.
 	 * @since Envoy Client v0.2-beta
 	 */
 	public static void exit(boolean force) {
-		if (!force && Settings.getInstance().isHideOnClose() && StatusTrayIcon.isSupported()) Context.getInstance().getStage().setIconified(true);
+		if (!force && Settings.getInstance().isHideOnClose() && StatusTrayIcon.isSupported())
+			Context.getInstance().getStage().setIconified(true);
 		else {
 			EventBus.getInstance().dispatch(new EnvoyCloseEvent());
 			System.exit(0);
diff --git a/client/src/main/java/envoy/client/net/Client.java b/client/src/main/java/envoy/client/net/Client.java
index 0db43ef..fe1c9e2 100644
--- a/client/src/main/java/envoy/client/net/Client.java
+++ b/client/src/main/java/envoy/client/net/Client.java
@@ -5,18 +5,19 @@ import java.net.Socket;
 import java.util.concurrent.TimeoutException;
 import java.util.logging.*;
 
-import envoy.client.data.*;
-import envoy.client.event.EnvoyCloseEvent;
+import dev.kske.eventbus.*;
+import dev.kske.eventbus.Event;
+
 import envoy.data.*;
 import envoy.event.*;
 import envoy.util.*;
 
-import dev.kske.eventbus.*;
-import dev.kske.eventbus.Event;
+import envoy.client.data.*;
+import envoy.client.event.EnvoyCloseEvent;
 
 /**
- * Establishes a connection to the server, performs a handshake and delivers
- * certain objects to the server.
+ * Establishes a connection to the server, performs a handshake and delivers certain objects to the
+ * server.
  *
  * @author Kai S. K. Engelbart
  * @author Maximilian K&auml;fer
@@ -44,26 +45,31 @@ public final class Client implements EventListener, Closeable {
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public Client() { eventBus.registerListener(this); }
+	public Client() {
+		eventBus.registerListener(this);
+	}
 
 	/**
-	 * Enters the online mode by acquiring a user ID from the server. As a
-	 * connection has to be established and a handshake has to be made, this method
-	 * will block for up to 5 seconds. If the handshake does exceed this time limit,
-	 * an exception is thrown.
+	 * Enters the online mode by acquiring a user ID from the server. As a connection has to be
+	 * established and a handshake has to be made, this method will block for up to 5 seconds. If
+	 * the handshake does exceed this time limit, an exception is thrown.
 	 *
 	 * @param credentials the login credentials of the user
 	 * @param cacheMap    the map of all caches needed
 	 * @throws TimeoutException     if the server could not be reached
 	 * @throws IOException          if the login credentials could not be written
-	 * @throws InterruptedException if the current thread is interrupted while
-	 *                              waiting for the handshake response
+	 * @throws InterruptedException if the current thread is interrupted while waiting for the
+	 *                              handshake response
 	 */
-	public void performHandshake(LoginCredentials credentials, CacheMap cacheMap) throws TimeoutException, IOException, InterruptedException {
-		if (online) throw new IllegalStateException("Handshake has already been performed successfully");
+	public void performHandshake(LoginCredentials credentials, CacheMap cacheMap)
+		throws TimeoutException, IOException, InterruptedException {
+		if (online)
+			throw new IllegalStateException("Handshake has already been performed successfully");
+		rejected = false;
 
 		// Establish TCP connection
-		logger.log(Level.FINER, String.format("Attempting connection to server %s:%d...", config.getServer(), config.getPort()));
+		logger.log(Level.FINER, String.format("Attempting connection to server %s:%d...",
+			config.getServer(), config.getPort()));
 		socket = new Socket(config.getServer(), config.getPort());
 		logger.log(Level.FINE, "Successfully established TCP connection to server");
 
@@ -75,8 +81,6 @@ public final class Client implements EventListener, Closeable {
 		receiver.registerProcessor(User.class, sender -> this.sender = sender);
 		receiver.registerProcessors(cacheMap.getMap());
 
-		rejected = false;
-
 		// Start receiver
 		receiver.start();
 
@@ -95,7 +99,10 @@ public final class Client implements EventListener, Closeable {
 				return;
 			}
 
-			if (System.currentTimeMillis() - start > 5000) throw new TimeoutException("Did not log in after 5 seconds");
+			if (System.currentTimeMillis() - start > 5000) {
+				rejected = true;
+				throw new TimeoutException("Did not log in after 5 seconds");
+			}
 			Thread.sleep(500);
 		}
 
@@ -104,14 +111,12 @@ public final class Client implements EventListener, Closeable {
 	}
 
 	/**
-	 * Initializes the {@link Receiver} used to process data sent from the server to
-	 * this client.
+	 * Initializes the {@link Receiver} used to process data sent from the server to this client.
 	 *
-	 * @param localDB  the local database used to persist the current
-	 *                 {@link IDGenerator}
+	 * @param localDB  the local database used to persist the current {@link IDGenerator}
 	 * @param cacheMap the map of all caches needed
-	 * @throws IOException if no {@link IDGenerator} is present and none could be
-	 *                     requested from the server
+	 * @throws IOException if no {@link IDGenerator} is present and none could be requested from the
+	 *                     server
 	 * @since Envoy Client v0.2-alpha
 	 */
 	public void initReceiver(LocalDB localDB, CacheMap cacheMap) throws IOException {
@@ -127,7 +132,8 @@ public final class Client implements EventListener, Closeable {
 		cacheMap.get(GroupMessageStatusChange.class).setProcessor(eventBus::dispatch);
 
 		// Request a generator if none is present or the existing one is consumed
-		if (!localDB.hasIDGenerator() || !localDB.getIDGenerator().hasNext()) requestIDGenerator();
+		if (!localDB.hasIDGenerator() || !localDB.getIDGenerator().hasNext())
+			requestIDGenerator();
 
 		// Relay caches
 		cacheMap.getMap().values().forEach(Cache::relay);
@@ -146,14 +152,14 @@ public final class Client implements EventListener, Closeable {
 		logger.log(Level.FINE, "Sending " + obj);
 		try {
 			SerializationUtils.writeBytesWithLength(obj, socket.getOutputStream());
-		} catch (IOException e) {
+		} catch (final IOException e) {
 			throw new RuntimeException(e);
 		}
 	}
 
 	/**
-	 * Sends a message to the server. The message's status will be incremented once
-	 * it was delivered successfully.
+	 * Sends a message to the server. The message's status will be incremented once it was delivered
+	 * successfully.
 	 *
 	 * @param message the message to send
 	 * @since Envoy Client v0.3-alpha
@@ -174,10 +180,12 @@ public final class Client implements EventListener, Closeable {
 	}
 
 	@Event(eventType = HandshakeRejection.class, priority = 1000)
-	private void onHandshakeRejection() { rejected = true; }
+	private void onHandshakeRejection() {
+		rejected = true;
+	}
 
 	@Override
-	@Event(eventType = EnvoyCloseEvent.class, priority = 800)
+	@Event(eventType = EnvoyCloseEvent.class, priority = 50)
 	public void close() {
 		if (online) {
 			logger.log(Level.INFO, "Closing connection...");
@@ -199,7 +207,10 @@ public final class Client implements EventListener, Closeable {
 	 * @throws IllegalStateException if the client is not online
 	 * @since Envoy Client v0.3-alpha
 	 */
-	private void checkOnline() throws IllegalStateException { if (!online) throw new IllegalStateException("Client is not online"); }
+	private void checkOnline() throws IllegalStateException {
+		if (!online)
+			throw new IllegalStateException("Client is not online");
+	}
 
 	/**
 	 * @return the {@link User} as which this client is logged in
diff --git a/client/src/main/java/envoy/client/net/Receiver.java b/client/src/main/java/envoy/client/net/Receiver.java
index 81e84fb..84d1e22 100644
--- a/client/src/main/java/envoy/client/net/Receiver.java
+++ b/client/src/main/java/envoy/client/net/Receiver.java
@@ -6,13 +6,12 @@ import java.util.*;
 import java.util.function.Consumer;
 import java.util.logging.*;
 
-import envoy.util.*;
-
 import dev.kske.eventbus.*;
 
+import envoy.util.*;
+
 /**
- * Receives objects from the server and passes them to processor objects based
- * on their class.
+ * Receives objects from the server and passes them to processor objects based on their class.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.3-alpha
@@ -40,8 +39,7 @@ public final class Receiver extends Thread {
 	}
 
 	/**
-	 * Starts the receiver loop. When an object is read, it is passed to the
-	 * appropriate processor.
+	 * Starts the receiver loop. When an object is read, it is passed to the appropriate processor.
 	 *
 	 * @since Envoy Client v0.3-alpha
 	 */
@@ -66,15 +64,19 @@ public final class Receiver extends Thread {
 					// Server has stopped sending, i.e. because he went offline
 					if (bytesRead == -1) {
 						isAlive = false;
-						logger.log(Level.INFO, "Lost connection to the server. Exiting receiver...");
+						logger.log(Level.INFO,
+							"Lost connection to the server. Exiting receiver...");
 						continue;
 					}
 					logger.log(Level.WARNING,
-							String.format("LV encoding violated: expected %d bytes, received %d bytes. Discarding object...", len, bytesRead));
+						String.format(
+							"LV encoding violated: expected %d bytes, received %d bytes. Discarding object...",
+							len, bytesRead));
 					continue;
 				}
 
-				try (ObjectInputStream oin = new ObjectInputStream(new ByteArrayInputStream(objBytes))) {
+				try (ObjectInputStream oin =
+					new ObjectInputStream(new ByteArrayInputStream(objBytes))) {
 					final Object obj = oin.readObject();
 					logger.log(Level.FINE, "Received " + obj);
 
@@ -83,12 +85,17 @@ public final class Receiver extends Thread {
 					final Consumer processor = processors.get(obj.getClass());
 
 					// Dispatch to the processor if present
-					if (processor != null) processor.accept(obj);
+					if (processor != null)
+						processor.accept(obj);
 					// Dispatch to the event bus if the object is an event without a processor
-					else if (obj instanceof IEvent) eventBus.dispatch((IEvent) obj);
+					else if (obj instanceof IEvent)
+						eventBus.dispatch((IEvent) obj);
 					// Notify if no processor could be located
-					else logger.log(Level.WARNING,
-							String.format("The received object has the %s for which no processor is defined.", obj.getClass()));
+					else
+						logger.log(Level.WARNING,
+							String.format(
+								"The received object has the %s for which no processor is defined.",
+								obj.getClass()));
 				}
 			} catch (final SocketException | EOFException e) {
 				// Connection probably closed by client.
@@ -100,14 +107,16 @@ public final class Receiver extends Thread {
 	}
 
 	/**
-	 * Adds an object processor to this {@link Receiver}. It will be called once an
-	 * object of the accepted class has been received.
+	 * Adds an object processor to this {@link Receiver}. It will be called once an object of the
+	 * accepted class has been received.
 	 *
 	 * @param processorClass the object class accepted by the processor
 	 * @param processor      the object processor
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public <T> void registerProcessor(Class<T> processorClass, Consumer<T> processor) { processors.put(processorClass, processor); }
+	public <T> void registerProcessor(Class<T> processorClass, Consumer<T> processor) {
+		processors.put(processorClass, processor);
+	}
 
 	/**
 	 * Adds a map of object processors to this {@link Receiver}.
@@ -115,12 +124,16 @@ public final class Receiver extends Thread {
 	 * @param processors the processors to add the processors to add
 	 * @since Envoy Client v0.1-beta
 	 */
-	public void registerProcessors(Map<Class<?>, ? extends Consumer<?>> processors) { this.processors.putAll(processors); }
+	public void registerProcessors(Map<Class<?>, ? extends Consumer<?>> processors) {
+		this.processors.putAll(processors);
+	}
 
 	/**
 	 * Removes all object processors registered at this {@link Receiver}.
 	 *
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public void removeAllProcessors() { processors.clear(); }
+	public void removeAllProcessors() {
+		processors.clear();
+	}
 }
diff --git a/client/src/main/java/envoy/client/net/WriteProxy.java b/client/src/main/java/envoy/client/net/WriteProxy.java
index 5ffd056..5cf62b5 100644
--- a/client/src/main/java/envoy/client/net/WriteProxy.java
+++ b/client/src/main/java/envoy/client/net/WriteProxy.java
@@ -2,15 +2,15 @@ package envoy.client.net;
 
 import java.util.logging.*;
 
-import envoy.client.data.*;
 import envoy.data.Message;
 import envoy.event.MessageStatusChange;
 import envoy.util.EnvoyLog;
 
+import envoy.client.data.*;
+
 /**
- * Implements methods to send {@link Message}s and
- * {@link MessageStatusChange}s to the server or cache them inside a
- * {@link LocalDB} depending on the online status.
+ * Implements methods to send {@link Message}s and {@link MessageStatusChange}s to the server or
+ * cache them inside a {@link LocalDB} depending on the online status.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.3-alpha
@@ -23,12 +23,11 @@ public final class WriteProxy {
 	private static final Logger logger = EnvoyLog.getLogger(WriteProxy.class);
 
 	/**
-	 * Initializes a write proxy using a client and a local database. The
-	 * corresponding cache processors are injected into the caches.
+	 * Initializes a write proxy using a client and a local database. The corresponding cache
+	 * processors are injected into the caches.
 	 *
 	 * @param client  the client instance used to send messages and events if online
-	 * @param localDB the local database used to cache messages and events if
-	 *                offline
+	 * @param localDB the local database used to cache messages and events if offline
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public WriteProxy(Client client, LocalDB localDB) {
@@ -47,34 +46,39 @@ public final class WriteProxy {
 	}
 
 	/**
-	 * Sends cached {@link Message}s and {@link MessageStatusChange}s to the
-	 * server.
+	 * Sends cached {@link Message}s and {@link MessageStatusChange}s to the server.
 	 *
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public void flushCache() { localDB.getCacheMap().getMap().values().forEach(Cache::relay); }
+	public void flushCache() {
+		localDB.getCacheMap().getMap().values().forEach(Cache::relay);
+	}
 
 	/**
-	 * Delivers a message to the server if online. Otherwise the message is cached
-	 * inside the local database.
+	 * Delivers a message to the server if online. Otherwise the message is cached inside the local
+	 * database.
 	 *
 	 * @param message the message to send
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public void writeMessage(Message message) {
-		if (client.isOnline()) client.sendMessage(message);
-		else localDB.getCacheMap().getApplicable(Message.class).accept(message);
+		if (client.isOnline())
+			client.sendMessage(message);
+		else
+			localDB.getCacheMap().getApplicable(Message.class).accept(message);
 	}
 
 	/**
-	 * Delivers a message status change event to the server if online. Otherwise the
-	 * event is cached inside the local database.
+	 * Delivers a message status change event to the server if online. Otherwise the event is cached
+	 * inside the local database.
 	 *
 	 * @param evt the event to send
 	 * @since Envoy Client v0.3-alpha
 	 */
 	public void writeMessageStatusChange(MessageStatusChange evt) {
-		if (client.isOnline()) client.send(evt);
-		else localDB.getCacheMap().getApplicable(MessageStatusChange.class).accept(evt);
+		if (client.isOnline())
+			client.send(evt);
+		else
+			localDB.getCacheMap().getApplicable(MessageStatusChange.class).accept(evt);
 	}
 }
diff --git a/client/src/main/java/envoy/client/ui/Restorable.java b/client/src/main/java/envoy/client/ui/Restorable.java
index 11d2a90..a7d404d 100644
--- a/client/src/main/java/envoy/client/ui/Restorable.java
+++ b/client/src/main/java/envoy/client/ui/Restorable.java
@@ -1,8 +1,8 @@
 package envoy.client.ui;
 
 /**
- * This interface defines an action that should be performed when a scene gets
- * restored from the scene stack in {@link SceneContext}.
+ * This interface defines an action that should be performed when a scene gets restored from the
+ * scene stack in {@link SceneContext}.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.1-beta
@@ -12,8 +12,7 @@ public interface Restorable {
 
 	/**
 	 * This method is getting called when a scene gets restored.<br>
-	 * Hence, it can contain anything that should be done when the underlying scene
-	 * gets restored.
+	 * Hence, it can contain anything that should be done when the underlying scene gets restored.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
diff --git a/client/src/main/java/envoy/client/ui/SceneContext.java b/client/src/main/java/envoy/client/ui/SceneContext.java
index 70bb662..8e42c33 100644
--- a/client/src/main/java/envoy/client/ui/SceneContext.java
+++ b/client/src/main/java/envoy/client/ui/SceneContext.java
@@ -9,20 +9,19 @@ import javafx.fxml.FXMLLoader;
 import javafx.scene.*;
 import javafx.stage.Stage;
 
+import dev.kske.eventbus.*;
+
+import envoy.util.EnvoyLog;
+
 import envoy.client.data.Settings;
 import envoy.client.data.shortcuts.*;
 import envoy.client.event.*;
-import envoy.util.EnvoyLog;
-
-import dev.kske.eventbus.*;
 
 /**
- * Manages a stack of scenes. The most recently added scene is displayed inside
- * a stage. When a scene is removed from the stack, its predecessor is
- * displayed.
+ * Manages a stack of scenes. The most recently added scene is displayed inside a stage. When a
+ * scene is removed from the stack, its predecessor is displayed.
  * <p>
- * When a scene is loaded, the style sheet for the current theme is applied to
- * it.
+ * When a scene is loaded, the style sheet for the current theme is applied to it.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
@@ -63,7 +62,9 @@ public final class SceneContext implements EventListener {
 		 */
 		public final String path;
 
-		SceneInfo(String path) { this.path = path; }
+		SceneInfo(String path) {
+			this.path = path;
+		}
 	}
 
 	private final Stage			stage;
@@ -97,7 +98,8 @@ public final class SceneContext implements EventListener {
 		loader.setController(null);
 
 		try {
-			final var	rootNode	= (Parent) loader.load(getClass().getResourceAsStream(sceneInfo.path));
+			final var	rootNode	=
+				(Parent) loader.load(getClass().getResourceAsStream(sceneInfo.path));
 			final var	scene		= new Scene(rootNode);
 			final var	controller	= loader.getController();
 			controllerStack.push(controller);
@@ -106,10 +108,13 @@ public final class SceneContext implements EventListener {
 			stage.setScene(scene);
 
 			// Supply the global custom keyboard shortcuts for that scene
-			scene.getAccelerators().putAll(GlobalKeyShortcuts.getInstance().getKeyboardShortcuts(sceneInfo));
+			scene.getAccelerators()
+				.putAll(GlobalKeyShortcuts.getInstance().getKeyboardShortcuts(sceneInfo));
 
 			// Supply the scene specific keyboard shortcuts
-			if (controller instanceof KeyboardMapping) scene.getAccelerators().putAll(((KeyboardMapping) controller).getKeyboardShortcuts());
+			if (controller instanceof KeyboardMapping)
+				scene.getAccelerators()
+					.putAll(((KeyboardMapping) controller).getKeyboardShortcuts());
 
 			// The LoginScene is the only scene not intended to be resized
 			// As strange as it seems, this is needed as otherwise the LoginScene won't be
@@ -119,7 +124,8 @@ public final class SceneContext implements EventListener {
 			applyCSS();
 			stage.show();
 		} catch (final IOException e) {
-			EnvoyLog.getLogger(SceneContext.class).log(Level.SEVERE, String.format("Could not load scene for %s: ", sceneInfo), e);
+			EnvoyLog.getLogger(SceneContext.class).log(Level.SEVERE,
+				String.format("Could not load scene for %s: ", sceneInfo), e);
 			throw new RuntimeException(e);
 		}
 	}
@@ -144,7 +150,8 @@ public final class SceneContext implements EventListener {
 			// If the controller implements the Restorable interface,
 			// the actions to perform on restoration will be executed here
 			final var controller = controllerStack.peek();
-			if (controller instanceof Restorable) ((Restorable) controller).onRestore();
+			if (controller instanceof Restorable)
+				((Restorable) controller).onRestore();
 		}
 		stage.show();
 	}
@@ -154,7 +161,8 @@ public final class SceneContext implements EventListener {
 			final var	styleSheets	= stage.getScene().getStylesheets();
 			final var	themeCSS	= "/css/" + settings.getCurrentTheme() + ".css";
 			styleSheets.clear();
-			styleSheets.addAll(getClass().getResource("/css/base.css").toExternalForm(), getClass().getResource(themeCSS).toExternalForm());
+			styleSheets.addAll(getClass().getResource("/css/base.css").toExternalForm(),
+				getClass().getResource(themeCSS).toExternalForm());
 		}
 	}
 
@@ -165,7 +173,9 @@ public final class SceneContext implements EventListener {
 	}
 
 	@Event(priority = 150, eventType = ThemeChangeEvent.class)
-	private void onThemeChange() { applyCSS(); }
+	private void onThemeChange() {
+		applyCSS();
+	}
 
 	/**
 	 * @param <T> the type of the controller
diff --git a/client/src/main/java/envoy/client/ui/Startup.java b/client/src/main/java/envoy/client/ui/Startup.java
index a93bf81..76fa54b 100644
--- a/client/src/main/java/envoy/client/ui/Startup.java
+++ b/client/src/main/java/envoy/client/ui/Startup.java
@@ -10,6 +10,12 @@ import javafx.scene.control.Alert;
 import javafx.scene.control.Alert.AlertType;
 import javafx.stage.Stage;
 
+import envoy.data.*;
+import envoy.data.User.UserStatus;
+import envoy.event.*;
+import envoy.exception.EnvoyException;
+import envoy.util.EnvoyLog;
+
 import envoy.client.data.*;
 import envoy.client.data.shortcuts.EnvoyShortcutConfig;
 import envoy.client.helper.ShutdownHelper;
@@ -17,11 +23,6 @@ import envoy.client.net.Client;
 import envoy.client.ui.SceneContext.SceneInfo;
 import envoy.client.ui.controller.LoginScene;
 import envoy.client.util.IconUtil;
-import envoy.data.*;
-import envoy.data.User.UserStatus;
-import envoy.event.*;
-import envoy.exception.EnvoyException;
-import envoy.util.EnvoyLog;
 
 /**
  * Handles application startup.
@@ -47,8 +48,8 @@ public final class Startup extends Application {
 	private static final Logger			logger	= EnvoyLog.getLogger(Startup.class);
 
 	/**
-	 * Loads the configuration, initializes the client and the local database and
-	 * delegates the rest of the startup process to {@link LoginScene}.
+	 * Loads the configuration, initializes the client and the local database and delegates the rest
+	 * of the startup process to {@link LoginScene}.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
@@ -57,7 +58,8 @@ public final class Startup extends Application {
 
 		// Initialize config and logger
 		try {
-			config.loadAll(Startup.class, "client.properties", getParameters().getRaw().toArray(new String[0]));
+			config.loadAll(Startup.class, "client.properties",
+				getParameters().getRaw().toArray(new String[0]));
 			EnvoyLog.initialize(config);
 		} catch (final IllegalStateException e) {
 			new Alert(AlertType.ERROR, "Error loading configuration values:\n" + e);
@@ -97,7 +99,8 @@ public final class Startup extends Application {
 			logger.info("Attempting authentication with token...");
 			localDB.loadUserData();
 			if (!performHandshake(
-					LoginCredentials.loginWithToken(localDB.getUser().getName(), localDB.getAuthToken(), VERSION, localDB.getLastSync())))
+				LoginCredentials.loginWithToken(localDB.getUser().getName(), localDB.getAuthToken(),
+					VERSION, localDB.getLastSync())))
 				sceneContext.load(SceneInfo.LOGIN_SCENE);
 		} else
 			// Load login scene
@@ -117,7 +120,8 @@ public final class Startup extends Application {
 		cacheMap.put(GroupMessage.class, new Cache<GroupMessage>());
 		cacheMap.put(MessageStatusChange.class, new Cache<MessageStatusChange>());
 		cacheMap.put(GroupMessageStatusChange.class, new Cache<GroupMessageStatusChange>());
-		final var originalStatus = localDB.getUser() == null ? UserStatus.ONLINE : localDB.getUser().getStatus();
+		final var originalStatus =
+			localDB.getUser() == null ? UserStatus.ONLINE : localDB.getUser().getStatus();
 		try {
 			client.performHandshake(credentials, cacheMap);
 			if (client.isOnline()) {
@@ -127,7 +131,8 @@ public final class Startup extends Application {
 				loadChatScene();
 				client.initReceiver(localDB, cacheMap);
 				return true;
-			} else return false;
+			} else
+				return false;
 		} catch (IOException | InterruptedException | TimeoutException e) {
 			logger.log(Level.INFO, "Could not connect to server. Entering offline mode...");
 			return attemptOfflineMode(credentials.getIdentifier());
@@ -135,8 +140,8 @@ public final class Startup extends Application {
 	}
 
 	/**
-	 * Attempts to load {@link envoy.client.ui.controller.ChatScene} in offline mode
-	 * for a given user.
+	 * Attempts to load {@link envoy.client.ui.controller.ChatScene} in offline mode for a given
+	 * user.
 	 *
 	 * @param identifier the identifier of the user - currently his username
 	 * @return whether the offline mode could be entered
@@ -146,7 +151,8 @@ public final class Startup extends Application {
 		try {
 			// Try entering offline mode
 			final User clientUser = localDB.getUsers().get(identifier);
-			if (clientUser == null) throw new EnvoyException("Could not enter offline mode: user name unknown");
+			if (clientUser == null)
+				throw new EnvoyException("Could not enter offline mode: user name unknown");
 			client.setSender(clientUser);
 			loadChatScene();
 			return true;
@@ -187,7 +193,9 @@ public final class Startup extends Application {
 		} catch (final FileNotFoundException e) {
 			// The local database file has not yet been created, probably first login
 		} catch (final Exception e) {
-			new Alert(AlertType.ERROR, "Error while loading local database: " + e + "\nChats will not be stored locally.").showAndWait();
+			new Alert(AlertType.ERROR,
+				"Error while loading local database: " + e + "\nChats will not be stored locally.")
+					.showAndWait();
 			logger.log(Level.WARNING, "Could not load local database: ", e);
 		}
 
@@ -197,7 +205,8 @@ public final class Startup extends Application {
 			context.getWriteProxy().flushCache();
 
 			// Inform the server that this user has a different user status than expected
-			if (!user.getStatus().equals(UserStatus.ONLINE)) client.send(new UserStatusChange(user));
+			if (!user.getStatus().equals(UserStatus.ONLINE))
+				client.send(new UserStatusChange(user));
 		} else
 
 			// Set all contacts to offline mode
@@ -211,7 +220,8 @@ public final class Startup extends Application {
 		final var stage = context.getStage();
 
 		// Pop LoginScene if present
-		if (!context.getSceneContext().isEmpty()) context.getSceneContext().pop();
+		if (!context.getSceneContext().isEmpty())
+			context.getSceneContext().pop();
 
 		// Load ChatScene
 		stage.setMinHeight(400);
@@ -221,15 +231,21 @@ public final class Startup extends Application {
 
 		// Exit or minimize the stage when a close request occurs
 		stage.setOnCloseRequest(
-				e -> { ShutdownHelper.exit(); if (Settings.getInstance().isHideOnClose() && StatusTrayIcon.isSupported()) e.consume(); });
+			e -> {
+				ShutdownHelper.exit();
+				if (Settings.getInstance().isHideOnClose() && StatusTrayIcon.isSupported())
+					e.consume();
+			});
 
 		if (StatusTrayIcon.isSupported()) {
 
 			// Initialize status tray icon
 			final var trayIcon = new StatusTrayIcon(stage);
 			Settings.getInstance().getItems().get("hideOnClose").setChangeHandler(c -> {
-				if ((Boolean) c) trayIcon.show();
-				else trayIcon.hide();
+				if ((Boolean) c)
+					trayIcon.show();
+				else
+					trayIcon.hide();
 			});
 		}
 
diff --git a/client/src/main/java/envoy/client/ui/chatscene/ChatSceneCommands.java b/client/src/main/java/envoy/client/ui/chatscene/ChatSceneCommands.java
index 475d210..680074a 100644
--- a/client/src/main/java/envoy/client/ui/chatscene/ChatSceneCommands.java
+++ b/client/src/main/java/envoy/client/ui/chatscene/ChatSceneCommands.java
@@ -8,19 +8,19 @@ import javafx.scene.control.*;
 import javafx.scene.control.Alert.AlertType;
 import javafx.scene.control.skin.VirtualFlow;
 
+import envoy.data.Message;
+import envoy.data.User.UserStatus;
+import envoy.util.EnvoyLog;
+
 import envoy.client.data.Context;
 import envoy.client.data.commands.*;
 import envoy.client.helper.ShutdownHelper;
 import envoy.client.ui.SceneContext.SceneInfo;
 import envoy.client.ui.controller.ChatScene;
 import envoy.client.util.*;
-import envoy.data.Message;
-import envoy.data.User.UserStatus;
-import envoy.util.EnvoyLog;
 
 /**
- * Contains all {@link SystemCommand}s used for
- * {@link envoy.client.ui.controller.ChatScene}.
+ * Contains all {@link SystemCommand}s used for {@link envoy.client.ui.controller.ChatScene}.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.3-beta
@@ -29,12 +29,13 @@ public final class ChatSceneCommands {
 
 	private final ListView<Message>		messageList;
 	private final SystemCommandMap		messageTextAreaCommands	= new SystemCommandMap();
-	private final SystemCommandBuilder	builder					= new SystemCommandBuilder(messageTextAreaCommands);
+	private final SystemCommandBuilder	builder					=
+		new SystemCommandBuilder(messageTextAreaCommands);
 
-	private static final String messageDependantCommandDescription = " the given message. Use s/S to use the selected message. Otherwise expects a number relative to the uppermost completely visible message.";
+	private static final String messageDependantCommandDescription =
+		" the given message. Use s/S to use the selected message. Otherwise expects a number relative to the uppermost completely visible message.";
 
 	/**
-	 *
 	 * @param messageList the message list to use for some commands
 	 * @param chatScene   the instance of {@code ChatScene} that uses this object
 	 * @since Envoy Client v0.3-beta
@@ -43,25 +44,33 @@ public final class ChatSceneCommands {
 		this.messageList = messageList;
 
 		// Error message initialization
-		builder.setAction(text -> { throw new RuntimeException(); }).setDescription("Shows an error message.").buildNoArg("error");
+		builder.setAction(text -> { throw new RuntimeException(); })
+			.setDescription("Shows an error message.").buildNoArg("error");
 
 		// Do A Barrel roll initialization
 		final var random = new Random();
-		builder.setAction(text -> chatScene.doABarrelRoll(Integer.parseInt(text.get(0)), Double.parseDouble(text.get(1))))
-			.setDefaults(Integer.toString(random.nextInt(3) + 1), Double.toString(random.nextDouble() * 3 + 1))
+		builder
+			.setAction(text -> chatScene.doABarrelRoll(Integer.parseInt(text.get(0)),
+				Double.parseDouble(text.get(1))))
+			.setDefaults(Integer.toString(random.nextInt(3) + 1),
+				Double.toString(random.nextDouble() * 3 + 1))
 			.setDescription("See for yourself :)")
 			.setNumberOfArguments(2)
 			.build("dabr");
 
 		// Logout initialization
-		builder.setAction(text -> UserUtil.logout()).setDescription("Logs you out.").buildNoArg("logout");
+		builder.setAction(text -> UserUtil.logout()).setDescription("Logs you out.")
+			.buildNoArg("logout");
 
 		// Exit initialization
-		builder.setAction(text -> ShutdownHelper.exit()).setNumberOfArguments(0).setDescription("Exits the program.").build("exit", false);
+		builder.setAction(text -> ShutdownHelper.exit()).setNumberOfArguments(0)
+			.setDescription("Exits the program.").build("exit", false);
 		builder.build("q");
 
 		// Open settings scene initialization
-		builder.setAction(text -> Context.getInstance().getSceneContext().load(SceneInfo.SETTINGS_SCENE))
+		builder
+			.setAction(
+				text -> Context.getInstance().getSceneContext().load(SceneInfo.SETTINGS_SCENE))
 			.setDescription("Opens the settings screen")
 			.buildNoArg("settings");
 
@@ -74,81 +83,106 @@ public final class ChatSceneCommands {
 				alert.setContentText("Please provide an existing status");
 				alert.showAndWait();
 			}
-		}).setDescription("Changes your status to the given status.").setNumberOfArguments(1).setDefaults("").build("status");
+		}).setDescription("Changes your status to the given status.").setNumberOfArguments(1)
+			.setDefaults("").build("status");
 
 		// Selection of a new message initialization
 		messageDependantAction("s",
-				m -> { messageList.getSelectionModel().clearSelection(); messageList.getSelectionModel().select(m); },
-				m -> true,
-				"Selects");
+			m -> {
+				messageList.getSelectionModel().clearSelection();
+				messageList.getSelectionModel().select(m);
+			},
+			m -> true,
+			"Selects");
 
 		// Copy text of selection initialization
-		messageDependantAction("cp", MessageUtil::copyMessageText, m -> !m.getText().isEmpty(), "Copies the text of");
+		messageDependantAction("cp", MessageUtil::copyMessageText, m -> !m.getText().isEmpty(),
+			"Copies the text of");
 
 		// Delete selection initialization
 		messageDependantAction("del", MessageUtil::deleteMessage, m -> true, "Deletes");
 
 		// Save attachment of selection initialization
-		messageDependantAction("save-att", MessageUtil::saveAttachment, Message::hasAttachment, "Saves the attachment of");
+		messageDependantAction("save-att", MessageUtil::saveAttachment, Message::hasAttachment,
+			"Saves the attachment of");
 	}
 
-	private void messageDependantAction(String command, Consumer<Message> action, Predicate<Message> additionalCheck, String description) {
+	private void messageDependantAction(String command, Consumer<Message> action,
+		Predicate<Message> additionalCheck, String description) {
 		builder.setAction(text -> {
 			final var positionalArgument = text.get(0).toLowerCase();
 
 			// the currently selected message was requested
 			if (positionalArgument.startsWith("s")) {
-				final var relativeString = positionalArgument.length() == 1 ? "" : positionalArgument.substring(1);
+				final var relativeString =
+					positionalArgument.length() == 1 ? "" : positionalArgument.substring(1);
 
 				// Only s has been used as input
 				if (positionalArgument.length() == 1) {
 					final var selectedMessage = messageList.getSelectionModel().getSelectedItem();
-					if (selectedMessage != null && additionalCheck.test(selectedMessage)) action.accept(selectedMessage);
+					if (selectedMessage != null && additionalCheck.test(selectedMessage))
+						action.accept(selectedMessage);
 					return;
 
 					// Either s++ or s-- has been requested
-				} else if (relativeString.equals("++") || relativeString.equals("--")) selectionNeighbor(action, additionalCheck, positionalArgument);
+				} else if (relativeString.equals("++") || relativeString.equals("--"))
+					selectionNeighbor(action, additionalCheck, positionalArgument);
 
 				// A message relative to the currently selected message should be used (i.e.
 				// s+4)
-				else useRelativeMessage(command, action, additionalCheck, relativeString, true);
+				else
+					useRelativeMessage(command, action, additionalCheck, relativeString, true);
 
 				// Either ++s or --s has been requested
 			} else if (positionalArgument.equals("--s") || positionalArgument.equals("++s"))
 				selectionNeighbor(action, additionalCheck, positionalArgument);
 
 			// Just a number is expected: ((+)4)
-			else useRelativeMessage(command, action, additionalCheck, positionalArgument, false);
-		}).setDefaults("s").setNumberOfArguments(1).setDescription(description.concat(messageDependantCommandDescription)).build(command);
+			else
+				useRelativeMessage(command, action, additionalCheck, positionalArgument, false);
+		}).setDefaults("s").setNumberOfArguments(1)
+			.setDescription(description.concat(messageDependantCommandDescription)).build(command);
 	}
 
-	private void selectionNeighbor(Consumer<Message> action, Predicate<Message> additionalCheck, final String positionalArgument) {
-		final var wantedIndex = messageList.getSelectionModel().getSelectedIndex() + (positionalArgument.contains("+") ? 1 : -1);
+	private void selectionNeighbor(Consumer<Message> action, Predicate<Message> additionalCheck,
+		final String positionalArgument) {
+		final var wantedIndex = messageList.getSelectionModel().getSelectedIndex()
+			+ (positionalArgument.contains("+") ? 1 : -1);
 		messageList.getSelectionModel().clearAndSelect(wantedIndex);
 		final var selectedMessage = messageList.getItems().get(wantedIndex);
-		if (selectedMessage != null && additionalCheck.test(selectedMessage)) action.accept(selectedMessage);
+		if (selectedMessage != null && additionalCheck.test(selectedMessage))
+			action.accept(selectedMessage);
 	}
 
-	private void useRelativeMessage(String command, Consumer<Message> action, Predicate<Message> additionalCheck, final String positionalArgument,
-			boolean useSelectedMessage) throws NumberFormatException {
-		final var	stripPlus	= positionalArgument.startsWith("+") ? positionalArgument.substring(1) : positionalArgument;
+	private void useRelativeMessage(String command, Consumer<Message> action,
+		Predicate<Message> additionalCheck, final String positionalArgument,
+		boolean useSelectedMessage) throws NumberFormatException {
+		final var	stripPlus	=
+			positionalArgument.startsWith("+") ? positionalArgument.substring(1)
+				: positionalArgument;
 		final var	incDec		= Integer.valueOf(stripPlus);
 		try {
 
 			// The currently selected message is the base message
 			if (useSelectedMessage) {
-				final var messageToUse = messageList.getItems().get(messageList.getSelectionModel().getSelectedIndex() + incDec);
-				if (messageToUse != null && additionalCheck.test(messageToUse)) action.accept(messageToUse);
+				final var messageToUse = messageList.getItems()
+					.get(messageList.getSelectionModel().getSelectedIndex() + incDec);
+				if (messageToUse != null && additionalCheck.test(messageToUse))
+					action.accept(messageToUse);
 
 				// The currently upmost completely visible message is the base message
 			} else {
 				final var messageToUse = messageList.getItems()
-					.get(((VirtualFlow<?>) messageList.lookup(".virtual-flow")).getFirstVisibleCell().getIndex() + 1 + incDec);
-				if (messageToUse != null && additionalCheck.test(messageToUse)) action.accept(messageToUse);
+					.get(((VirtualFlow<?>) messageList.lookup(".virtual-flow"))
+						.getFirstVisibleCell().getIndex() + 1 + incDec);
+				if (messageToUse != null && additionalCheck.test(messageToUse))
+					action.accept(messageToUse);
 			}
 		} catch (final IndexOutOfBoundsException e) {
 			EnvoyLog.getLogger(ChatSceneCommands.class)
-				.log(Level.INFO, " A non-existing message was requested by the user for System command " + command);
+				.log(Level.INFO,
+					" A non-existing message was requested by the user for System command "
+						+ command);
 		}
 	}
 
diff --git a/client/src/main/java/envoy/client/ui/chatscene/TextInputContextMenu.java b/client/src/main/java/envoy/client/ui/chatscene/TextInputContextMenu.java
index e11b6ca..b653240 100644
--- a/client/src/main/java/envoy/client/ui/chatscene/TextInputContextMenu.java
+++ b/client/src/main/java/envoy/client/ui/chatscene/TextInputContextMenu.java
@@ -7,8 +7,8 @@ import javafx.scene.control.*;
 import javafx.scene.input.Clipboard;
 
 /**
- * Displays a context menu that offers an additional option when one of
- * its menu items has been clicked.
+ * Displays a context menu that offers an additional option when one of its menu items has been
+ * clicked.
  * <p>
  * Current options are:
  * <ul>
@@ -24,9 +24,8 @@ import javafx.scene.input.Clipboard;
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.2-beta
- * @apiNote please refrain from using
- *          {@link ContextMenu#setOnShowing(EventHandler)} as this is already
- *          used by this component
+ * @apiNote please refrain from using {@link ContextMenu#setOnShowing(EventHandler)} as this is
+ *          already used by this component
  */
 public class TextInputContextMenu extends ContextMenu {
 
@@ -40,8 +39,8 @@ public class TextInputContextMenu extends ContextMenu {
 	private final MenuItem	selectAllMI	= new MenuItem("Select all");
 
 	/**
-	 * Creates a new {@code TextInputContextMenu} with an optional action when
-	 * this menu was clicked. Currently shows:
+	 * Creates a new {@code TextInputContextMenu} with an optional action when this menu was
+	 * clicked. Currently shows:
 	 * <ul>
 	 * <li>undo</li>
 	 * <li>redo</li>
@@ -53,14 +52,12 @@ public class TextInputContextMenu extends ContextMenu {
 	 * <li>Select all</li>
 	 * </ul>
 	 *
-	 * @param control         the text input component to display this
-	 *                        {@code ContextMenu}
-	 * @param menuItemClicked the second action to perform when a menu item of this
-	 *                        context menu has been clicked
+	 * @param control         the text input component to display this {@code ContextMenu}
+	 * @param menuItemClicked the second action to perform when a menu item of this context menu has
+	 *                        been clicked
 	 * @since Envoy Client v0.2-beta
-	 * @apiNote please refrain from using
-	 *          {@link ContextMenu#setOnShowing(EventHandler)} as this is already
-	 *          used by this component
+	 * @apiNote please refrain from using {@link ContextMenu#setOnShowing(EventHandler)} as this is
+	 *          already used by this component
 	 */
 	public TextInputContextMenu(TextInputControl control, Consumer<ActionEvent> menuItemClicked) {
 
@@ -100,7 +97,11 @@ public class TextInputContextMenu extends ContextMenu {
 		getItems().add(selectAllMI);
 	}
 
-	private EventHandler<ActionEvent> addAction(Consumer<ActionEvent> originalAction, Consumer<ActionEvent> additionalAction) {
-		return e -> { originalAction.accept(e); additionalAction.accept(e); };
+	private EventHandler<ActionEvent> addAction(Consumer<ActionEvent> originalAction,
+		Consumer<ActionEvent> additionalAction) {
+		return e -> {
+			originalAction.accept(e);
+			additionalAction.accept(e);
+		};
 	}
 }
diff --git a/client/src/main/java/envoy/client/ui/chatscene/package-info.java b/client/src/main/java/envoy/client/ui/chatscene/package-info.java
index 12938c6..24b78b0 100644
--- a/client/src/main/java/envoy/client/ui/chatscene/package-info.java
+++ b/client/src/main/java/envoy/client/ui/chatscene/package-info.java
@@ -1,6 +1,6 @@
 /**
  * Contains classes that influence the appearance and behavior of ChatScene.
- * 
+ *
  * @author Leon Hofmeister
  * @since Envoy Client v0.3-beta
  */
diff --git a/client/src/main/java/envoy/client/ui/control/AudioControl.java b/client/src/main/java/envoy/client/ui/control/AudioControl.java
index fc2263b..75e6076 100644
--- a/client/src/main/java/envoy/client/ui/control/AudioControl.java
+++ b/client/src/main/java/envoy/client/ui/control/AudioControl.java
@@ -6,10 +6,11 @@ import javafx.scene.control.*;
 import javafx.scene.control.Alert.AlertType;
 import javafx.scene.layout.HBox;
 
-import envoy.client.data.audio.AudioPlayer;
 import envoy.exception.EnvoyException;
 import envoy.util.EnvoyLog;
 
+import envoy.client.data.audio.AudioPlayer;
+
 /**
  * Enables the play back of audio clips through a button.
  *
@@ -18,7 +19,7 @@ import envoy.util.EnvoyLog;
  */
 public final class AudioControl extends HBox {
 
-	private AudioPlayer player = new AudioPlayer();
+	private final AudioPlayer player = new AudioPlayer();
 
 	private static final Logger logger = EnvoyLog.getLogger(AudioControl.class);
 
diff --git a/client/src/main/java/envoy/client/ui/control/ChatControl.java b/client/src/main/java/envoy/client/ui/control/ChatControl.java
index 353bdaf..de50085 100644
--- a/client/src/main/java/envoy/client/ui/control/ChatControl.java
+++ b/client/src/main/java/envoy/client/ui/control/ChatControl.java
@@ -9,8 +9,8 @@ import envoy.client.data.*;
 import envoy.client.util.IconUtil;
 
 /**
- * Displays a chat using a contact control for the recipient and a label for the
- * unread message count.
+ * Displays a chat using a contact control for the recipient and a label for the unread message
+ * count.
  *
  * @see ContactControl
  * @author Leon Hofmeister
@@ -19,7 +19,7 @@ import envoy.client.util.IconUtil;
 public final class ChatControl extends HBox {
 
 	private static final Image userIcon = IconUtil.loadIconThemeSensitive("user_icon", 32),
-			groupIcon = IconUtil.loadIconThemeSensitive("group_icon", 32);
+		groupIcon = IconUtil.loadIconThemeSensitive("group_icon", 32);
 
 	/**
 	 * Creates a new {@code ChatControl}.
@@ -32,7 +32,8 @@ public final class ChatControl extends HBox {
 		setPadding(new Insets(0, 0, 3, 0));
 
 		// Profile picture
-		final var contactProfilePic = new ProfilePicImageView(chat instanceof GroupChat ? groupIcon : userIcon, 32);
+		final var contactProfilePic =
+			new ProfilePicImageView(chat instanceof GroupChat ? groupIcon : userIcon, 32);
 		getChildren().add(contactProfilePic);
 
 		// Spacing
diff --git a/client/src/main/java/envoy/client/ui/control/ContactControl.java b/client/src/main/java/envoy/client/ui/control/ContactControl.java
index 93b33d1..a4bec8a 100644
--- a/client/src/main/java/envoy/client/ui/control/ContactControl.java
+++ b/client/src/main/java/envoy/client/ui/control/ContactControl.java
@@ -6,9 +6,8 @@ import javafx.scene.layout.VBox;
 import envoy.data.*;
 
 /**
- * Displays information about a contact in two rows. The first row contains the
- * name. The second row contains the online status (user) or the member count
- * (group).
+ * Displays information about a contact in two rows. The first row contains the name. The second row
+ * contains the online status (user) or the member count (group).
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.2-beta
@@ -29,23 +28,24 @@ public final class ContactControl extends VBox {
 		getChildren().add(nameLabel);
 
 		// Online status (user) or member count (group)
-		getChildren().add(contact instanceof User ? new UserStatusLabel((User) contact) : new GroupSizeLabel((Group) contact));
+		getChildren().add(contact instanceof User ? new UserStatusLabel((User) contact)
+			: new GroupSizeLabel((Group) contact));
 
 		getStyleClass().add("list-element");
 	}
 
 	/**
-	 * Replaces the info label of this {@code ContactControl} with an updated
-	 * version.
+	 * Replaces the info label of this {@code ContactControl} with an updated version.
 	 * <p>
-	 * This method should be called when the status of the underlying user or the
-	 * size of the underlying group has changed.
+	 * This method should be called when the status of the underlying user or the size of the
+	 * underlying group has changed.
 	 *
 	 * @since Envoy Client v0.3-beta
-	 * @apiNote will produce buggy results if contact control gets updated so that
-	 *          the info label is no longer on index 1.
+	 * @apiNote will produce buggy results if contact control gets updated so that the info label is
+	 *          no longer on index 1.
 	 */
 	public void replaceInfoLabel() {
-		getChildren().set(1, contact instanceof User ? new UserStatusLabel((User) contact) : new GroupSizeLabel((Group) contact));
+		getChildren().set(1, contact instanceof User ? new UserStatusLabel((User) contact)
+			: new GroupSizeLabel((Group) contact));
 	}
 }
diff --git a/client/src/main/java/envoy/client/ui/control/GroupSizeLabel.java b/client/src/main/java/envoy/client/ui/control/GroupSizeLabel.java
index 8413744..b6e284c 100644
--- a/client/src/main/java/envoy/client/ui/control/GroupSizeLabel.java
+++ b/client/src/main/java/envoy/client/ui/control/GroupSizeLabel.java
@@ -16,5 +16,8 @@ public final class GroupSizeLabel extends Label {
 	 * @param recipient the group whose members to show
 	 * @since Envoy Client v0.3-beta
 	 */
-	public GroupSizeLabel(Group recipient) { super(recipient.getContacts().size() + " members"); }
+	public GroupSizeLabel(Group recipient) {
+		super(recipient.getContacts().size() + " member"
+			+ (recipient.getContacts().size() != 1 ? "s" : ""));
+	}
 }
diff --git a/client/src/main/java/envoy/client/ui/control/MessageControl.java b/client/src/main/java/envoy/client/ui/control/MessageControl.java
index 0cd14c4..8a947eb 100644
--- a/client/src/main/java/envoy/client/ui/control/MessageControl.java
+++ b/client/src/main/java/envoy/client/ui/control/MessageControl.java
@@ -11,13 +11,14 @@ import javafx.scene.control.*;
 import javafx.scene.image.*;
 import javafx.scene.layout.*;
 
-import envoy.client.data.*;
-import envoy.client.net.Client;
-import envoy.client.util.*;
 import envoy.data.*;
 import envoy.data.Message.MessageStatus;
 import envoy.util.EnvoyLog;
 
+import envoy.client.data.*;
+import envoy.client.net.Client;
+import envoy.client.util.*;
+
 /**
  * This class transforms a single {@link Message} into a UI component.
  *
@@ -33,13 +34,15 @@ public final class MessageControl extends Label {
 	private final Client	client	= context.getClient();
 
 	private static final Context					context			= Context.getInstance();
-	private static final DateTimeFormatter			dateFormat		= DateTimeFormatter.ofPattern("dd.MM.yyyy HH:mm:ss")
-		.withZone(ZoneId.systemDefault());
-	private static final Map<MessageStatus, Image>	statusImages	= IconUtil.loadByEnum(MessageStatus.class, 16);
-	private static final Logger						logger			= EnvoyLog.getLogger(MessageControl.class);
+	private static final DateTimeFormatter			dateFormat		=
+		DateTimeFormatter.ofPattern("dd.MM.yyyy HH:mm:ss")
+			.withZone(ZoneId.systemDefault());
+	private static final Map<MessageStatus, Image>	statusImages	=
+		IconUtil.loadByEnum(MessageStatus.class, 16);
+	private static final Logger						logger			=
+		EnvoyLog.getLogger(MessageControl.class);
 
 	/**
-	 *
 	 * @param message the message that should be formatted
 	 * @since Envoy Client v0.1-beta
 	 */
@@ -107,7 +110,9 @@ public final class MessageControl extends Label {
 			switch (message.getAttachment().getType()) {
 				case PICTURE:
 					vbox.getChildren()
-						.add(new ImageView(new Image(new ByteArrayInputStream(message.getAttachment().getData()), 256, 256, true, true)));
+						.add(new ImageView(
+							new Image(new ByteArrayInputStream(message.getAttachment().getData()),
+								256, 256, true, true)));
 					break;
 				case VIDEO:
 					break;
@@ -138,7 +143,8 @@ public final class MessageControl extends Label {
 			hBoxBottom.setAlignment(Pos.BOTTOM_RIGHT);
 			getStyleClass().add("own-message");
 			hbox.setAlignment(Pos.CENTER_RIGHT);
-		} else getStyleClass().add("received-message");
+		} else
+			getStyleClass().add("received-message");
 		vbox.getChildren().add(hBoxBottom);
 		// Adjusting height and weight of the cell to the corresponding ListView
 		paddingProperty().setValue(new Insets(5, 20, 5, 20));
@@ -146,11 +152,13 @@ public final class MessageControl extends Label {
 		setGraphic(vbox);
 	}
 
-	private void loadMessageInfoScene(Message message) { logger.log(Level.FINEST, "message info scene was requested for " + message); }
+	private void loadMessageInfoScene(Message message) {
+		logger.log(Level.FINEST, "message info scene was requested for " + message);
+	}
 
 	/**
-	 * @return whether the message stored by this {@code MessageControl} has been
-	 *         sent by this user of Envoy
+	 * @return whether the message stored by this {@code MessageControl} has been sent by this user
+	 *         of Envoy
 	 * @since Envoy Client v0.1-beta
 	 */
 	public boolean isOwnMessage() { return ownMessage; }
diff --git a/client/src/main/java/envoy/client/ui/control/ProfilePicImageView.java b/client/src/main/java/envoy/client/ui/control/ProfilePicImageView.java
index 778b026..1cfa5d5 100644
--- a/client/src/main/java/envoy/client/ui/control/ProfilePicImageView.java
+++ b/client/src/main/java/envoy/client/ui/control/ProfilePicImageView.java
@@ -16,7 +16,9 @@ public final class ProfilePicImageView extends ImageView {
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
-	public ProfilePicImageView() { this(null); }
+	public ProfilePicImageView() {
+		this(null);
+	}
 
 	/**
 	 * Creates a new {@code ProfilePicImageView}.
@@ -24,17 +26,20 @@ public final class ProfilePicImageView extends ImageView {
 	 * @param image the image to display
 	 * @since Envoy Client v0.2-beta
 	 */
-	public ProfilePicImageView(Image image) { this(image, 40); }
+	public ProfilePicImageView(Image image) {
+		this(image, 40);
+	}
 
 	/**
 	 * Creates a new {@code ProfilePicImageView}.
 	 *
 	 * @param image           the image to display
-	 * @param sizeAndRounding the size and rounding for a circular
-	 *                        {@code ProfilePicImageView}
+	 * @param sizeAndRounding the size and rounding for a circular {@code ProfilePicImageView}
 	 * @since Envoy Client v0.2-beta
 	 */
-	public ProfilePicImageView(Image image, double sizeAndRounding) { this(image, sizeAndRounding, sizeAndRounding); }
+	public ProfilePicImageView(Image image, double sizeAndRounding) {
+		this(image, sizeAndRounding, sizeAndRounding);
+	}
 
 	/**
 	 * Creates a new {@code ProfilePicImageView}.
diff --git a/client/src/main/java/envoy/client/ui/control/QuickSelectControl.java b/client/src/main/java/envoy/client/ui/control/QuickSelectControl.java
index 0e1b2e5..b9c0f39 100644
--- a/client/src/main/java/envoy/client/ui/control/QuickSelectControl.java
+++ b/client/src/main/java/envoy/client/ui/control/QuickSelectControl.java
@@ -8,25 +8,26 @@ import javafx.scene.image.ImageView;
 import javafx.scene.layout.*;
 import javafx.scene.shape.Rectangle;
 
+import envoy.data.User;
+
 import envoy.client.util.IconUtil;
-import envoy.data.*;
 
 /**
- * Displays an {@link User} as a quick select control which is used in the
- * quick select list.
- * 
+ * Displays an {@link User} as a quick select control which is used in the quick select list.
+ *
  * @author Maximilian K&auml;fer
  * @since Envoy Client v0.3-beta
  */
 public class QuickSelectControl extends VBox {
 
-	private User user;
+	private final User user;
 
 	/**
 	 * Creates an instance of the {@code QuickSelectControl}.
-	 * 
-	 * @param user the contact whose data is used to create this instance.
-	 * @param action the action to perform when a contact is removed with this control as a parameter
+	 *
+	 * @param user   the contact whose data is used to create this instance.
+	 * @param action the action to perform when a contact is removed with this control as a
+	 *               parameter
 	 * @since Envoy Client v0.3-beta
 	 */
 	public QuickSelectControl(User user, Consumer<QuickSelectControl> action) {
@@ -44,7 +45,8 @@ public class QuickSelectControl extends VBox {
 		picHold.setPrefHeight(35);
 		picHold.setMaxHeight(35);
 		picHold.setMinHeight(35);
-		var			contactProfilePic	= new ImageView(IconUtil.loadIconThemeSensitive("user_icon", 32));
+		var			contactProfilePic	=
+			new ImageView(IconUtil.loadIconThemeSensitive("user_icon", 32));
 		final var	clip				= new Rectangle();
 		clip.setWidth(32);
 		clip.setHeight(32);
diff --git a/client/src/main/java/envoy/client/ui/controller/ChatScene.java b/client/src/main/java/envoy/client/ui/controller/ChatScene.java
index c2b0ef1..c7d6034 100644
--- a/client/src/main/java/envoy/client/ui/controller/ChatScene.java
+++ b/client/src/main/java/envoy/client/ui/controller/ChatScene.java
@@ -24,6 +24,17 @@ import javafx.scene.shape.Rectangle;
 import javafx.stage.FileChooser;
 import javafx.util.Duration;
 
+import dev.kske.eventbus.*;
+import dev.kske.eventbus.Event;
+
+import envoy.data.*;
+import envoy.data.Attachment.AttachmentType;
+import envoy.data.Message.MessageStatus;
+import envoy.event.*;
+import envoy.event.contact.UserOperation;
+import envoy.exception.EnvoyException;
+import envoy.util.EnvoyLog;
+
 import envoy.client.data.*;
 import envoy.client.data.audio.AudioRecorder;
 import envoy.client.event.*;
@@ -33,16 +44,6 @@ import envoy.client.ui.chatscene.*;
 import envoy.client.ui.control.*;
 import envoy.client.ui.listcell.*;
 import envoy.client.util.*;
-import envoy.data.*;
-import envoy.data.Attachment.AttachmentType;
-import envoy.data.Message.MessageStatus;
-import envoy.event.*;
-import envoy.event.contact.ContactOperation;
-import envoy.exception.EnvoyException;
-import envoy.util.EnvoyLog;
-
-import dev.kske.eventbus.*;
-import dev.kske.eventbus.Event;
 
 /**
  * Controller for the chat scene.
@@ -91,9 +92,6 @@ public final class ChatScene implements EventListener, Restorable {
 	@FXML
 	private Label topBarStatusLabel;
 
-	@FXML
-	private MenuItem deleteContactMenuItem;
-
 	@FXML
 	private ImageView attachmentView;
 
@@ -142,9 +140,11 @@ public final class ChatScene implements EventListener, Restorable {
 	private final WriteProxy	writeProxy			= context.getWriteProxy();
 	private final SceneContext	sceneContext		= context.getSceneContext();
 	private final AudioRecorder	recorder			= new AudioRecorder();
-	private final Tooltip		onlyIfOnlineTooltip	= new Tooltip("You need to be online to do this");
+	private final Tooltip		onlyIfOnlineTooltip	=
+		new Tooltip("You need to be online to do this");
 
-	private static Image DEFAULT_ATTACHMENT_VIEW_IMAGE = IconUtil.loadIconThemeSensitive("attachment_present", 20);
+	private static Image DEFAULT_ATTACHMENT_VIEW_IMAGE =
+		IconUtil.loadIconThemeSensitive("attachment_present", 20);
 
 	private static final Settings	settings			= Settings.getInstance();
 	private static final EventBus	eventBus			= EventBus.getInstance();
@@ -165,19 +165,24 @@ public final class ChatScene implements EventListener, Restorable {
 
 		// Initialize message and user rendering
 		messageList.setCellFactory(MessageListCell::new);
-		chatList.setCellFactory(new ListCellFactory<>(ChatControl::new));
+		chatList.setCellFactory(ChatListCell::new);
 
 		// JavaFX provides an internal way of populating the context menu of a text
 		// area.
 		// We, however, need additional functionality.
-		messageTextArea.setContextMenu(new TextInputContextMenu(messageTextArea, e -> checkKeyCombination(null)));
+		messageTextArea.setContextMenu(
+			new TextInputContextMenu(messageTextArea, e -> checkKeyCombination(null)));
 
 		// Set the icons of buttons and image views
-		settingsButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("settings", DEFAULT_ICON_SIZE)));
-		voiceButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
-		attachmentButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("attachment", DEFAULT_ICON_SIZE)));
+		settingsButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("settings", DEFAULT_ICON_SIZE)));
+		voiceButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
+		attachmentButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("attachment", DEFAULT_ICON_SIZE)));
 		attachmentView.setImage(DEFAULT_ATTACHMENT_VIEW_IMAGE);
-		messageSearchButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("search", DEFAULT_ICON_SIZE)));
+		messageSearchButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("search", DEFAULT_ICON_SIZE)));
 		clientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
 		onlyIfOnlineTooltip.setShowDelay(Duration.millis(250));
 		final var clip = new Rectangle();
@@ -191,7 +196,6 @@ public final class ChatScene implements EventListener, Restorable {
 
 		// Set the design of the box in the upper-left corner
 		settingsButton.setAlignment(Pos.BOTTOM_RIGHT);
-		HBox.setHgrow(spaceBetweenUserAndSettingsButton, Priority.ALWAYS);
 		generateOwnStatusControl();
 
 		Platform.runLater(() -> {
@@ -199,15 +203,19 @@ public final class ChatScene implements EventListener, Restorable {
 
 			// no check will be performed in case it has already been disabled - a negative
 			// GroupCreationResult might have been returned
-			if (!newGroupButton.isDisabled()) newGroupButton.setDisable(!online);
+			if (!newGroupButton.isDisabled())
+				newGroupButton.setDisable(!online);
 			newContactButton.setDisable(!online);
-			if (online) try {
-				Tooltip.uninstall(contactSpecificOnlineOperations, onlyIfOnlineTooltip);
-				contactSearchTab.setContent(new FXMLLoader().load(getClass().getResourceAsStream("/fxml/ContactSearchTab.fxml")));
-				groupCreationTab.setContent(new FXMLLoader().load(getClass().getResourceAsStream("/fxml/GroupCreationTab.fxml")));
-			} catch (final IOException e) {
-				logger.log(Level.SEVERE, "An error occurred when attempting to load tabs: ", e);
-			}
+			if (online)
+				try {
+					Tooltip.uninstall(contactSpecificOnlineOperations, onlyIfOnlineTooltip);
+					contactSearchTab.setContent(new FXMLLoader()
+						.load(getClass().getResourceAsStream("/fxml/ContactSearchTab.fxml")));
+					groupCreationTab.setContent(new FXMLLoader()
+						.load(getClass().getResourceAsStream("/fxml/GroupCreationTab.fxml")));
+				} catch (final IOException e) {
+					logger.log(Level.SEVERE, "An error occurred when attempting to load tabs: ", e);
+				}
 			else {
 				Tooltip.install(contactSpecificOnlineOperations, onlyIfOnlineTooltip);
 				updateInfoLabel("You are offline", "info-label-warning");
@@ -216,7 +224,9 @@ public final class ChatScene implements EventListener, Restorable {
 	}
 
 	@Event(eventType = BackEvent.class)
-	private void onBackEvent() { tabPane.getSelectionModel().select(Tabs.CONTACT_LIST.ordinal()); }
+	private void onBackEvent() {
+		tabPane.getSelectionModel().select(Tabs.CONTACT_LIST.ordinal());
+	}
 
 	@Event(includeSubtypes = true)
 	private void onMessage(Message message) {
@@ -225,7 +235,9 @@ public final class ChatScene implements EventListener, Restorable {
 		// Exceptions: this user is the sender (sync) or group message (group is
 		// recipient)
 		final var	ownMessage	= message.getSenderID() == localDB.getUser().getID();
-		final var	recipientID	= message instanceof GroupMessage || ownMessage ? message.getRecipientID() : message.getSenderID();
+		final var	recipientID	=
+			message instanceof GroupMessage || ownMessage ? message.getRecipientID()
+				: message.getSenderID();
 
 		localDB.getChat(recipientID).ifPresent(chat -> {
 			Platform.runLater(() -> {
@@ -235,13 +247,15 @@ public final class ChatScene implements EventListener, Restorable {
 				if (chat.equals(currentChat)) {
 					currentChat.read(writeProxy);
 					scrollToMessageListEnd();
-				} else if (!ownMessage && message.getStatus() != MessageStatus.READ) chat.incrementUnreadAmount();
+				} else if (!ownMessage && message.getStatus() != MessageStatus.READ)
+					chat.incrementUnreadAmount();
 
 				// Move chat with most recent unread messages to the top
 				chats.getSource().remove(chat);
 				((ObservableList<Chat>) chats.getSource()).add(0, chat);
 
-				if (chat.equals(currentChat)) chatList.getSelectionModel().select(0);
+				if (chat.equals(currentChat))
+					chatList.getSelectionModel().select(0);
 			});
 		});
 	}
@@ -251,9 +265,10 @@ public final class ChatScene implements EventListener, Restorable {
 
 		// Update UI if in current chat and the current user was the sender of the
 		// message
-		if (currentChat != null) localDB.getMessage(evt.getID())
-			.filter(msg -> msg.getSenderID() == client.getSender().getID())
-			.ifPresent(msg -> Platform.runLater(messageList::refresh));
+		if (currentChat != null)
+			localDB.getMessage(evt.getID())
+				.filter(msg -> msg.getSenderID() == client.getSender().getID())
+				.ifPresent(msg -> Platform.runLater(messageList::refresh));
 	}
 
 	@Event
@@ -271,18 +286,25 @@ public final class ChatScene implements EventListener, Restorable {
 	}
 
 	@Event
-	private void onContactOperation(ContactOperation operation) {
-		final var contact = operation.get();
-		switch (operation.getOperationType()) {
-			case ADD:
-				if (contact instanceof User) localDB.getUsers().put(contact.getName(), (User) contact);
-				final var chat = contact instanceof User ? new Chat(contact) : new GroupChat(client.getSender(), contact);
-				Platform.runLater(() -> ((ObservableList<Chat>) chats.getSource()).add(0, chat));
-				break;
-			case REMOVE:
-				Platform.runLater(() -> chats.getSource().removeIf(c -> c.getRecipient().equals(contact)));
-				break;
-		}
+	private void onUserOperation(UserOperation operation) {
+
+		// All ADD dependent logic resides in LocalDB
+		if (operation.getOperationType().equals(ElementOperation.REMOVE))
+			Platform.runLater(() -> disableChat(new ContactDisabled(operation.get())));
+	}
+
+	@Event
+	private void onGroupResize(GroupResize resize) {
+		final var chatFound = localDB.getChat(resize.getGroupID());
+		chatFound.ifPresent(chat -> Platform.runLater(() -> {
+			chatList.refresh();
+
+			// Update the top-bar status label if all conditions apply
+			if (currentChat != null && currentChat.getRecipient().equals(chat.getRecipient()))
+				topBarStatusLabel
+					.setText(chat.getRecipient().getContacts().size() + " member"
+						+ (currentChat.getRecipient().getContacts().size() != 1 ? "s" : ""));
+		}));
 	}
 
 	@Event(eventType = NoAttachments.class)
@@ -298,31 +320,43 @@ public final class ChatScene implements EventListener, Restorable {
 		});
 	}
 
-	@Event
-	private void onGroupCreationResult(GroupCreationResult result) { Platform.runLater(() -> newGroupButton.setDisable(!result.get())); }
+	@Event(priority = 150)
+	private void onGroupCreationResult(GroupCreationResult result) {
+		Platform.runLater(() -> newGroupButton.setDisable(result.get() == null));
+	}
 
 	@Event(eventType = ThemeChangeEvent.class)
 	private void onThemeChange() {
-		settingsButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("settings", DEFAULT_ICON_SIZE)));
-		voiceButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
-		attachmentButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("attachment", DEFAULT_ICON_SIZE)));
+		settingsButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("settings", DEFAULT_ICON_SIZE)));
+		voiceButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
+		attachmentButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("attachment", DEFAULT_ICON_SIZE)));
 		DEFAULT_ATTACHMENT_VIEW_IMAGE = IconUtil.loadIconThemeSensitive("attachment_present", 20);
-		attachmentView.setImage(isCustomAttachmentImage ? attachmentView.getImage() : DEFAULT_ATTACHMENT_VIEW_IMAGE);
-		messageSearchButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("search", DEFAULT_ICON_SIZE)));
+		attachmentView.setImage(
+			isCustomAttachmentImage ? attachmentView.getImage() : DEFAULT_ATTACHMENT_VIEW_IMAGE);
+		messageSearchButton.setGraphic(
+			new ImageView(IconUtil.loadIconThemeSensitive("search", DEFAULT_ICON_SIZE)));
 		clientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
 		chatList.setCellFactory(new ListCellFactory<>(ChatControl::new));
 		messageList.setCellFactory(MessageListCell::new);
-		// TODO: cache image
 		if (currentChat != null)
-			if (currentChat.getRecipient() instanceof User) recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
-			else recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("group_icon", 43));
+			if (currentChat.getRecipient() instanceof User)
+				recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
+			else
+				recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("group_icon", 43));
 	}
 
 	@Event(eventType = Logout.class, priority = 200)
-	private void onLogout() { eventBus.removeListener(this); }
+	private void onLogout() {
+		eventBus.removeListener(this);
+	}
 
 	@Override
-	public void onRestore() { updateRemainingCharsLabel(); }
+	public void onRestore() {
+		updateRemainingCharsLabel();
+	}
 
 	/**
 	 * Actions to perform when the list of contacts has been clicked.
@@ -331,9 +365,13 @@ public final class ChatScene implements EventListener, Restorable {
 	 */
 	@FXML
 	private void chatListClicked() {
-		if (chatList.getSelectionModel().isEmpty()) return;
+		if (chatList.getSelectionModel().isEmpty())
+			return;
+		final var chat = chatList.getSelectionModel().getSelectedItem();
+		if (chat == null)
+			return;
 
-		final var user = chatList.getSelectionModel().getSelectedItem().getRecipient();
+		final var user = chat.getRecipient();
 		if (user != null && (currentChat == null || !user.equals(currentChat.getRecipient()))) {
 
 			// LEON: JFC <===> JAVA FRIED CHICKEN <=/=> Java Foundation Classes
@@ -345,7 +383,6 @@ public final class ChatScene implements EventListener, Restorable {
 			final var scrollIndex = messageList.getItems().size() - currentChat.getUnreadAmount();
 			messageList.scrollTo(scrollIndex);
 			logger.log(Level.FINEST, "Loading chat with " + user + " at index " + scrollIndex);
-			deleteContactMenuItem.setText("Delete " + user.getName());
 
 			// Read the current chat
 			currentChat.read(writeProxy);
@@ -353,7 +390,8 @@ public final class ChatScene implements EventListener, Restorable {
 			// Discard the pending attachment
 			if (recorder.isRecording()) {
 				recorder.cancel();
-				voiceButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
+				voiceButton.setGraphic(new ImageView(
+					IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
 				voiceButton.setText(null);
 			}
 			pendingAttachment = null;
@@ -361,22 +399,32 @@ public final class ChatScene implements EventListener, Restorable {
 
 			remainingChars.setVisible(true);
 			remainingChars
-				.setText(String.format("remaining chars: %d/%d", MAX_MESSAGE_LENGTH - messageTextArea.getText().length(), MAX_MESSAGE_LENGTH));
+				.setText(String.format("remaining chars: %d/%d",
+					MAX_MESSAGE_LENGTH - messageTextArea.getText().length(), MAX_MESSAGE_LENGTH));
 		}
-		messageTextArea.setDisable(currentChat == null || postingPermanentlyDisabled);
-		voiceButton.setDisable(!recorder.isSupported());
-		attachmentButton.setDisable(false);
+
+		// Enable or disable the necessary UI controls
+		final var chatEditable = currentChat == null || currentChat.isDisabled();
+		messageTextArea.setDisable(chatEditable || postingPermanentlyDisabled);
+		voiceButton.setDisable(!recorder.isSupported() || chatEditable);
+		attachmentButton.setDisable(chatEditable);
 		chatList.refresh();
 
+		// Design the top bar
 		if (currentChat != null) {
 			topBarContactLabel.setText(currentChat.getRecipient().getName());
+			topBarContactLabel.setVisible(true);
+			topBarStatusLabel.setVisible(true);
 			if (currentChat.getRecipient() instanceof User) {
 				final var status = ((User) currentChat.getRecipient()).getStatus().toString();
 				topBarStatusLabel.setText(status);
+				topBarStatusLabel.getStyleClass().clear();
 				topBarStatusLabel.getStyleClass().add(status.toLowerCase());
 				recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("user_icon", 43));
 			} else {
-				topBarStatusLabel.setText(currentChat.getRecipient().getContacts().size() + " members");
+				topBarStatusLabel
+					.setText(currentChat.getRecipient().getContacts().size() + " member"
+						+ (currentChat.getRecipient().getContacts().size() != 1 ? "s" : ""));
 				topBarStatusLabel.getStyleClass().clear();
 				recipientProfilePic.setImage(IconUtil.loadIconThemeSensitive("group_icon", 43));
 			}
@@ -386,7 +434,6 @@ public final class ChatScene implements EventListener, Restorable {
 			clip.setArcHeight(43);
 			clip.setArcWidth(43);
 			recipientProfilePic.setClip(clip);
-
 			messageSearchButton.setVisible(true);
 		}
 	}
@@ -397,7 +444,9 @@ public final class ChatScene implements EventListener, Restorable {
 	 * @since Envoy Client v0.1-beta
 	 */
 	@FXML
-	private void settingsButtonClicked() { sceneContext.load(SceneContext.SceneInfo.SETTINGS_SCENE); }
+	private void settingsButtonClicked() {
+		sceneContext.load(SceneContext.SceneInfo.SETTINGS_SCENE);
+	}
 
 	/**
 	 * Actions to perform when the "Add Contact" - Button has been clicked.
@@ -405,10 +454,14 @@ public final class ChatScene implements EventListener, Restorable {
 	 * @since Envoy Client v0.1-beta
 	 */
 	@FXML
-	private void addContactButtonClicked() { tabPane.getSelectionModel().select(Tabs.CONTACT_SEARCH.ordinal()); }
+	private void addContactButtonClicked() {
+		tabPane.getSelectionModel().select(Tabs.CONTACT_SEARCH.ordinal());
+	}
 
 	@FXML
-	private void groupCreationButtonClicked() { tabPane.getSelectionModel().select(Tabs.GROUP_CREATION.ordinal()); }
+	private void groupCreationButtonClicked() {
+		tabPane.getSelectionModel().select(Tabs.GROUP_CREATION.ordinal());
+	}
 
 	@FXML
 	private void voiceButtonClicked() {
@@ -417,15 +470,19 @@ public final class ChatScene implements EventListener, Restorable {
 				if (!recorder.isRecording()) {
 					Platform.runLater(() -> {
 						voiceButton.setText("Recording");
-						voiceButton.setGraphic(new ImageView(IconUtil.loadIcon("microphone_recording", DEFAULT_ICON_SIZE)));
+						voiceButton.setGraphic(new ImageView(
+							IconUtil.loadIcon("microphone_recording", DEFAULT_ICON_SIZE)));
 					});
 					recorder.start();
 				} else {
 					pendingAttachment = new Attachment(recorder.finish(), "Voice_recording_"
-							+ DateTimeFormatter.ofPattern("yyyy_MM_dd-HH_mm_ss").format(LocalDateTime.now()) + "." + AudioRecorder.FILE_FORMAT,
-							AttachmentType.VOICE);
+						+ DateTimeFormatter.ofPattern("yyyy_MM_dd-HH_mm_ss")
+							.format(LocalDateTime.now())
+						+ "." + AudioRecorder.FILE_FORMAT,
+						AttachmentType.VOICE);
 					Platform.runLater(() -> {
-						voiceButton.setGraphic(new ImageView(IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
+						voiceButton.setGraphic(new ImageView(
+							IconUtil.loadIconThemeSensitive("microphone", DEFAULT_ICON_SIZE)));
 						voiceButton.setText(null);
 						checkPostConditions(false);
 						updateAttachmentView(true);
@@ -433,7 +490,8 @@ public final class ChatScene implements EventListener, Restorable {
 				}
 			} catch (final EnvoyException e) {
 				logger.log(Level.SEVERE, "Could not record audio: ", e);
-				Platform.runLater(new Alert(AlertType.ERROR, "Could not record audio")::showAndWait);
+				Platform
+					.runLater(new Alert(AlertType.ERROR, "Could not record audio")::showAndWait);
 			}
 		}).start();
 	}
@@ -447,15 +505,16 @@ public final class ChatScene implements EventListener, Restorable {
 		fileChooser.setInitialDirectory(new File(System.getProperty("user.home")));
 		fileChooser.getExtensionFilters()
 			.addAll(new FileChooser.ExtensionFilter("Pictures", "*.png", "*.jpg", "*.bmp", "*.gif"),
-					new FileChooser.ExtensionFilter("Videos", "*.mp4"),
-					new FileChooser.ExtensionFilter("All Files", "*.*"));
+				new FileChooser.ExtensionFilter("Videos", "*.mp4"),
+				new FileChooser.ExtensionFilter("All Files", "*.*"));
 		final var file = fileChooser.showOpenDialog(sceneContext.getStage());
 
 		if (file != null) {
 
 			// Check max file size
 			if (file.length() > 16E6) {
-				new Alert(AlertType.WARNING, "The selected file exceeds the size limit of 16MB!").showAndWait();
+				new Alert(AlertType.WARNING, "The selected file exceeds the size limit of 16MB!")
+					.showAndWait();
 				return;
 			}
 
@@ -477,7 +536,8 @@ public final class ChatScene implements EventListener, Restorable {
 				checkPostConditions(false);
 				// Setting the preview image as image of the attachmentView
 				if (type == AttachmentType.PICTURE) {
-					attachmentView.setImage(new Image(new ByteArrayInputStream(fileBytes), DEFAULT_ICON_SIZE, DEFAULT_ICON_SIZE, true, true));
+					attachmentView.setImage(new Image(new ByteArrayInputStream(fileBytes),
+						DEFAULT_ICON_SIZE, DEFAULT_ICON_SIZE, true, true));
 					isCustomAttachmentImage = true;
 				}
 				attachmentView.setVisible(true);
@@ -488,8 +548,7 @@ public final class ChatScene implements EventListener, Restorable {
 	}
 
 	/**
-	 * Rotates every element in our application by {@code rotations}*360° in
-	 * {@code an}.
+	 * Rotates every element in our application by {@code rotations}*360° in {@code an}.
 	 *
 	 * @param rotations     the amount of times the scene is rotated by 360°
 	 * @param animationTime the time in seconds that this animation lasts
@@ -506,7 +565,8 @@ public final class ChatScene implements EventListener, Restorable {
 		final var rotatableNodes = ReflectionUtil.getAllDeclaredNodeVariables(this);
 		for (final var node : rotatableNodes) {
 			// Sets the animation duration to {animationTime}
-			final var rotateTransition = new RotateTransition(Duration.seconds(animationTime), node);
+			final var rotateTransition =
+				new RotateTransition(Duration.seconds(animationTime), node);
 			// rotates every element {rotations} times
 			rotateTransition.setByAngle(rotations * 360);
 			rotateTransition.play();
@@ -517,9 +577,8 @@ public final class ChatScene implements EventListener, Restorable {
 	}
 
 	/**
-	 * Checks the text length of the {@code messageTextArea}, adjusts the
-	 * {@code remainingChars} label and checks whether to send the message
-	 * automatically.
+	 * Checks the text length of the {@code messageTextArea}, adjusts the {@code remainingChars}
+	 * label and checks whether to send the message automatically.
 	 *
 	 * @param e the key event that will be analyzed for a post request
 	 * @since Envoy Client v0.1-beta
@@ -532,29 +591,33 @@ public final class ChatScene implements EventListener, Restorable {
 
 		// Sending an IsTyping event if none has been sent for
 		// IsTyping#millisecondsActive
-		if (client.isOnline() && currentChat.getLastWritingEvent() + IsTyping.millisecondsActive <= System.currentTimeMillis()) {
+		if (client.isOnline() && currentChat.getLastWritingEvent()
+			+ IsTyping.millisecondsActive <= System.currentTimeMillis()) {
 			client.send(new IsTyping(getChatID(), currentChat.getRecipient().getID()));
 			currentChat.lastWritingEventWasNow();
 		}
 
 		// KeyPressed will be called before the char has been added to the text, hence
 		// this is needed for the first char
-		if (messageTextArea.getText().length() == 1 && e != null) checkPostConditions(e);
+		if (messageTextArea.getText().length() == 1 && e != null)
+			checkPostConditions(e);
 
 		// This is needed for the messageTA context menu
-		else if (e == null) checkPostConditions(false);
+		else if (e == null)
+			checkPostConditions(false);
 	}
 
 	/**
-	 * Returns the id that should be used to send things to the server: the id of
-	 * 'our' {@link User} if the recipient of that object is another User, else the
-	 * id of the {@link Group} 'our' user is sending to.
+	 * Returns the id that should be used to send things to the server: the id of 'our' {@link User}
+	 * if the recipient of that object is another User, else the id of the {@link Group} 'our' user
+	 * is sending to.
 	 *
 	 * @return an id that can be sent to the server
 	 * @since Envoy Client v0.2-beta
 	 */
 	private long getChatID() {
-		return currentChat.getRecipient() instanceof User ? client.getSender().getID() : currentChat.getRecipient().getID();
+		return currentChat.getRecipient() instanceof User ? client.getSender().getID()
+			: currentChat.getRecipient().getID();
 	}
 
 	/**
@@ -564,21 +627,25 @@ public final class ChatScene implements EventListener, Restorable {
 	@FXML
 	private void checkPostConditions(KeyEvent e) {
 		final var	enterPressed	= e.getCode() == KeyCode.ENTER;
-		final var	messagePosted	= enterPressed ? settings.isEnterToSend() ? !e.isControlDown() : e.isControlDown() : false;
+		final var	messagePosted	=
+			enterPressed ? settings.isEnterToSend() ? !e.isControlDown() : e.isControlDown()
+				: false;
 		if (messagePosted) {
 
 			// Removing an inserted line break if added by pressing enter
 			final var	text			= messageTextArea.getText();
 			final var	textPosition	= messageTextArea.getCaretPosition() - 1;
 			if (!e.isControlDown() && !text.isEmpty() && text.charAt(textPosition) == '\n')
-				messageTextArea.setText(new StringBuilder(text).deleteCharAt(textPosition).toString());
+				messageTextArea
+					.setText(new StringBuilder(text).deleteCharAt(textPosition).toString());
 		}
 
 		// if control is pressed, the enter press is originally invalidated. Here it'll
 		// be inserted again
 		else if (enterPressed && e.isControlDown()) {
 			var caretPosition = messageTextArea.getCaretPosition();
-			messageTextArea.setText(new StringBuilder(messageTextArea.getText()).insert(caretPosition, '\n').toString());
+			messageTextArea.setText(new StringBuilder(messageTextArea.getText())
+				.insert(caretPosition, '\n').toString());
 			messageTextArea.positionCaret(++caretPosition);
 		}
 		checkPostConditions(messagePosted);
@@ -586,8 +653,10 @@ public final class ChatScene implements EventListener, Restorable {
 
 	private void checkPostConditions(boolean postMessage) {
 		if (!postingPermanentlyDisabled) {
-			if (!postButton.isDisabled() && postMessage) postMessage();
-			postButton.setDisable(messageTextArea.getText().isBlank() && pendingAttachment == null || currentChat == null);
+			if (!postButton.isDisabled() && postMessage)
+				postMessage();
+			postButton.setDisable(messageTextArea.getText().isBlank() && pendingAttachment == null
+				|| currentChat == null);
 		} else {
 			final var noMoreMessaging = "Go online to send messages";
 			if (!infoLabel.getText().equals(noMoreMessaging))
@@ -621,13 +690,14 @@ public final class ChatScene implements EventListener, Restorable {
 	private void updateRemainingCharsLabel() {
 		final var	currentLength	= messageTextArea.getText().length();
 		final var	remainingLength	= MAX_MESSAGE_LENGTH - currentLength;
-		remainingChars.setText(String.format("remaining chars: %d/%d", remainingLength, MAX_MESSAGE_LENGTH));
+		remainingChars
+			.setText(String.format("remaining chars: %d/%d", remainingLength, MAX_MESSAGE_LENGTH));
 		remainingChars.setTextFill(Color.rgb(currentLength, remainingLength, 0, 1));
 	}
 
 	/**
-	 * Sends a new {@link Message} or {@link GroupMessage} to the server based on
-	 * the text entered in the {@code messageTextArea} and the given attachment.
+	 * Sends a new {@link Message} or {@link GroupMessage} to the server based on the text entered
+	 * in the {@code messageTextArea} and the given attachment.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
@@ -644,8 +714,9 @@ public final class ChatScene implements EventListener, Restorable {
 		final var text = messageTextArea.getText().strip();
 		if (!commands.getChatSceneCommands().executeIfPresent(text)) {
 			// Creating the message and its metadata
-			final var builder = new MessageBuilder(localDB.getUser().getID(), currentChat.getRecipient().getID(), localDB.getIDGenerator())
-				.setText(text);
+			final var builder = new MessageBuilder(localDB.getUser().getID(),
+				currentChat.getRecipient().getID(), localDB.getIDGenerator())
+					.setText(text);
 			// Setting an attachment, if present
 			if (pendingAttachment != null) {
 				builder.setAttachment(pendingAttachment);
@@ -653,8 +724,9 @@ public final class ChatScene implements EventListener, Restorable {
 				updateAttachmentView(false);
 			}
 			// Building the final message
-			final var message = currentChat.getRecipient() instanceof Group ? builder.buildGroupMessage((Group) currentChat.getRecipient())
-					: builder.build();
+			final var message = currentChat.getRecipient() instanceof Group
+				? builder.buildGroupMessage((Group) currentChat.getRecipient())
+				: builder.build();
 
 			// Send message
 			writeProxy.writeMessage(message);
@@ -665,14 +737,15 @@ public final class ChatScene implements EventListener, Restorable {
 			Platform.runLater(() -> {
 				chats.getSource().remove(currentChat);
 				((ObservableList<Chat>) chats.getSource()).add(0, currentChat);
-				chatList.getSelectionModel().select(0);
 				localDB.getChats().remove(currentChat);
 				localDB.getChats().add(0, currentChat);
+				chatList.getSelectionModel().select(0);
 			});
 			scrollToMessageListEnd();
 
 			// Request a new ID generator if all IDs were used
-			if (!localDB.getIDGenerator().hasNext() && client.isOnline()) client.requestIDGenerator();
+			if (!localDB.getIDGenerator().hasNext() && client.isOnline())
+				client.requestIDGenerator();
 		}
 
 		// Clear text field and disable post button
@@ -687,14 +760,16 @@ public final class ChatScene implements EventListener, Restorable {
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
-	private void scrollToMessageListEnd() { messageList.scrollTo(messageList.getItems().size() - 1); }
+	private void scrollToMessageListEnd() {
+		messageList.scrollTo(messageList.getItems().size() - 1);
+	}
 
 	/**
 	 * Updates the {@code infoLabel}.
 	 *
 	 * @param text        the text to use
-	 * @param infoLabelID the id the the {@code infoLabel} should have so that it
-	 *                    can be styled accordingly in CSS
+	 * @param infoLabelID the id the the {@code infoLabel} should have so that it can be styled
+	 *                    accordingly in CSS
 	 * @since Envoy Client v0.1-beta
 	 */
 	private void updateInfoLabel(String text, String infoLabelID) {
@@ -705,14 +780,16 @@ public final class ChatScene implements EventListener, Restorable {
 
 	/**
 	 * Updates the {@code attachmentView} in terms of visibility.<br>
-	 * Additionally resets the shown image to {@code DEFAULT_ATTACHMENT_VIEW_IMAGE}
-	 * if another image is currently present.
+	 * Additionally resets the shown image to {@code DEFAULT_ATTACHMENT_VIEW_IMAGE} if another image
+	 * is currently present.
 	 *
 	 * @param visible whether the {@code attachmentView} should be displayed
 	 * @since Envoy Client v0.1-beta
 	 */
 	private void updateAttachmentView(boolean visible) {
-		if (!attachmentView.getImage().equals(DEFAULT_ATTACHMENT_VIEW_IMAGE)) attachmentView.setImage(DEFAULT_ATTACHMENT_VIEW_IMAGE);
+		if (!(attachmentView.getImage() == null
+			|| attachmentView.getImage().equals(DEFAULT_ATTACHMENT_VIEW_IMAGE)))
+			attachmentView.setImage(DEFAULT_ATTACHMENT_VIEW_IMAGE);
 		attachmentView.setVisible(visible);
 	}
 
@@ -727,19 +804,66 @@ public final class ChatScene implements EventListener, Restorable {
 			// Else prepend it to the HBox children
 			final var ownUserControl = new ContactControl(localDB.getUser());
 			ownUserControl.setAlignment(Pos.CENTER_LEFT);
+			HBox.setHgrow(ownUserControl, Priority.NEVER);
 			ownContactControl.getChildren().add(0, ownUserControl);
 		}
 	}
 
-	// Context menu actions
+	/**
+	 * Redesigns the UI when the {@link Chat} of the given contact has been marked as disabled.
+	 *
+	 * @param event the contact whose chat got disabled
+	 * @since Envoy Client v0.3-beta
+	 */
+	@Event
+	public void disableChat(ContactDisabled event) {
+		chatList.refresh();
+		final var recipient = event.get();
 
-	@FXML
-	private void deleteContact() { try {} catch (final NullPointerException e) {} }
+		// Decrement member count for groups
+		if (recipient instanceof Group)
+			topBarStatusLabel.setText(recipient.getContacts().size() + " member"
+				+ (recipient.getContacts().size() != 1 ? "s" : ""));
+		if (currentChat != null && currentChat.getRecipient().equals(recipient)) {
+			messageTextArea.setDisable(true);
+			voiceButton.setDisable(true);
+			attachmentButton.setDisable(true);
+			pendingAttachment = null;
+			messageList.getStyleClass().clear();
+			messageList.getStyleClass().add("disabled-chat");
+		}
+	}
+
+	/**
+	 * Resets every component back to its inital state before a chat was selected.
+	 *
+	 * @since Envoy Client v0.3-beta
+	 */
+	public void resetState() {
+		currentChat = null;
+		chatList.getSelectionModel().clearSelection();
+		messageList.getItems().clear();
+		messageTextArea.setDisable(true);
+		attachmentView.setImage(null);
+		topBarContactLabel.setVisible(false);
+		topBarStatusLabel.setVisible(false);
+		messageSearchButton.setVisible(false);
+		messageTextArea.clear();
+		messageTextArea.setDisable(true);
+		attachmentButton.setDisable(true);
+		voiceButton.setDisable(true);
+		remainingChars.setVisible(false);
+		pendingAttachment = null;
+		recipientProfilePic.setImage(null);
+		if (recorder.isRecording())
+			recorder.cancel();
+	}
 
 	@FXML
 	private void copyAndPostMessage() {
 		final var messageText = messageTextArea.getText();
-		Toolkit.getDefaultToolkit().getSystemClipboard().setContents(new StringSelection(messageText), null);
+		Toolkit.getDefaultToolkit().getSystemClipboard()
+			.setContents(new StringSelection(messageText), null);
 		final var	image				= attachmentView.getImage();
 		final var	messageAttachment	= pendingAttachment;
 		postMessage();
@@ -747,7 +871,8 @@ public final class ChatScene implements EventListener, Restorable {
 		updateRemainingCharsLabel();
 		postButton.setDisable(messageText.isBlank());
 		attachmentView.setImage(image);
-		if (attachmentView.getImage() != null) attachmentView.setVisible(true);
+		if (attachmentView.getImage() != null)
+			attachmentView.setVisible(true);
 		pendingAttachment = messageAttachment;
 	}
 
@@ -756,11 +881,14 @@ public final class ChatScene implements EventListener, Restorable {
 	 *
 	 * @since Envoy Client v0.3-beta
 	 */
-	public void clearMessageSelection() { messageList.getSelectionModel().clearSelection(); }
+	public void clearMessageSelection() {
+		messageList.getSelectionModel().clearSelection();
+	}
 
 	@FXML
 	private void searchContacts() {
 		chats.setPredicate(contactSearch.getText().isBlank() ? c -> true
-				: c -> c.getRecipient().getName().toLowerCase().contains(contactSearch.getText().toLowerCase()));
+			: c -> c.getRecipient().getName().toLowerCase()
+				.contains(contactSearch.getText().toLowerCase()));
 	}
 }
diff --git a/client/src/main/java/envoy/client/ui/controller/ContactSearchTab.java b/client/src/main/java/envoy/client/ui/controller/ContactSearchTab.java
index b573345..3445329 100644
--- a/client/src/main/java/envoy/client/ui/controller/ContactSearchTab.java
+++ b/client/src/main/java/envoy/client/ui/controller/ContactSearchTab.java
@@ -7,28 +7,28 @@ import javafx.fxml.FXML;
 import javafx.scene.control.*;
 import javafx.scene.control.Alert.AlertType;
 
+import dev.kske.eventbus.*;
+
+import envoy.data.User;
+import envoy.event.ElementOperation;
+import envoy.event.contact.*;
+import envoy.util.EnvoyLog;
+
 import envoy.client.data.Context;
 import envoy.client.event.BackEvent;
 import envoy.client.helper.AlertHelper;
 import envoy.client.net.Client;
 import envoy.client.ui.control.ContactControl;
 import envoy.client.ui.listcell.ListCellFactory;
-import envoy.data.User;
-import envoy.event.ElementOperation;
-import envoy.event.contact.*;
-import envoy.util.EnvoyLog;
-
-import dev.kske.eventbus.*;
 
 /**
- * Provides a search bar in which a user name (substring) can be entered. The
- * users with a matching name are then displayed inside a list view. A
- * {@link UserSearchRequest} is sent on every keystroke.
+ * Provides a search bar in which a user name (substring) can be entered. The users with a matching
+ * name are then displayed inside a list view. A {@link UserSearchRequest} is sent on every
+ * keystroke.
  * <p>
  * <i>The actual search algorithm is implemented on the server.
  * <p>
- * To create a group, a button is available that loads the
- * {@link GroupCreationTab}.
+ * To create a group, a button is available that loads the {@link GroupCreationTab}.
  *
  * @author Leon Hofmeister
  * @author Maximilian K&auml;fer
@@ -59,16 +59,22 @@ public class ContactSearchTab implements EventListener {
 
 	@Event
 	private void onUserSearchResult(UserSearchResult result) {
-		Platform.runLater(() -> { userList.getItems().clear(); userList.getItems().addAll(result.get()); });
+		Platform.runLater(() -> {
+			userList.getItems().clear();
+			userList.getItems().addAll(result.get());
+		});
 	}
 
 	@Event
-	private void onContactOperation(ContactOperation operation) {
+	private void onUserOperation(UserOperation operation) {
 		final var contact = operation.get();
-		if (operation.getOperationType() == ElementOperation.ADD) Platform.runLater(() -> {
-			userList.getItems().remove(contact);
-			if (currentlySelectedUser != null && currentlySelectedUser.equals(contact) && alert.isShowing()) alert.close();
-		});
+		if (operation.getOperationType() == ElementOperation.ADD)
+			Platform.runLater(() -> {
+				userList.getItems().remove(contact);
+				if (currentlySelectedUser != null && currentlySelectedUser.equals(contact)
+					&& alert.isShowing())
+					alert.close();
+			});
 	}
 
 	/**
@@ -79,13 +85,15 @@ public class ContactSearchTab implements EventListener {
 	@FXML
 	private void sendRequest() {
 		final var text = searchBar.getText().strip();
-		if (!text.isBlank()) client.send(new UserSearchRequest(text));
-		else userList.getItems().clear();
+		if (!text.isBlank())
+			client.send(new UserSearchRequest(text));
+		else
+			userList.getItems().clear();
 	}
 
 	/**
-	 * Clears the text in the search bar and the items shown in the list.
-	 * Additionally disables both clear and search button.
+	 * Clears the text in the search bar and the items shown in the list. Additionally disables both
+	 * clear and search button.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
@@ -96,8 +104,7 @@ public class ContactSearchTab implements EventListener {
 	}
 
 	/**
-	 * Sends an {@link ContactOperation} for the selected user to the
-	 * server.
+	 * Sends an {@link UserOperation} for the selected user to the server.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
@@ -106,7 +113,8 @@ public class ContactSearchTab implements EventListener {
 		final var user = userList.getSelectionModel().getSelectedItem();
 		if (user != null) {
 			currentlySelectedUser = user;
-			alert.setContentText("Add user " + currentlySelectedUser.getName() + " to your contacts?");
+			alert.setContentText(
+				"Add user " + currentlySelectedUser.getName() + " to your contacts?");
 			AlertHelper.confirmAction(alert, this::addAsContact);
 		}
 	}
@@ -114,7 +122,7 @@ public class ContactSearchTab implements EventListener {
 	private void addAsContact() {
 
 		// Sends the event to the server
-		final var event = new ContactOperation(currentlySelectedUser, ElementOperation.ADD);
+		final var event = new UserOperation(currentlySelectedUser, ElementOperation.ADD);
 		client.send(event);
 
 		// Removes the chosen user and updates the UI
@@ -124,5 +132,8 @@ public class ContactSearchTab implements EventListener {
 	}
 
 	@FXML
-	private void backButtonClicked() { eventBus.dispatch(new BackEvent()); }
+	private void backButtonClicked() {
+		searchBar.setText("");
+		eventBus.dispatch(new BackEvent());
+	}
 }
diff --git a/client/src/main/java/envoy/client/ui/controller/GroupCreationTab.java b/client/src/main/java/envoy/client/ui/controller/GroupCreationTab.java
index 23ec485..39f414d 100644
--- a/client/src/main/java/envoy/client/ui/controller/GroupCreationTab.java
+++ b/client/src/main/java/envoy/client/ui/controller/GroupCreationTab.java
@@ -10,25 +10,25 @@ import javafx.scene.control.*;
 import javafx.scene.input.MouseEvent;
 import javafx.scene.layout.HBox;
 
+import dev.kske.eventbus.*;
+
+import envoy.data.*;
+import envoy.event.GroupCreation;
+import envoy.event.contact.UserOperation;
+import envoy.util.Bounds;
+
 import envoy.client.data.*;
 import envoy.client.event.BackEvent;
 import envoy.client.ui.control.*;
 import envoy.client.ui.listcell.ListCellFactory;
-import envoy.data.*;
-import envoy.event.GroupCreation;
-import envoy.event.contact.ContactOperation;
-import envoy.util.Bounds;
-
-import dev.kske.eventbus.*;
 
 /**
- * Provides a group creation interface. A group name can be entered in the text
- * field at the top. Available users (local chat recipients) are displayed
- * inside a list and can be selected (multiple selection available).
+ * Provides a group creation interface. A group name can be entered in the text field at the top.
+ * Available users (local chat recipients) are displayed inside a list and can be selected (multiple
+ * selection available).
  * <p>
- * When the group creation button is pressed, a {@link GroupCreation} is sent to
- * the server. This controller enforces a valid group name and a non-empty
- * member list (excluding the client user).
+ * When the group creation button is pressed, a {@link GroupCreation} is sent to the server. This
+ * controller enforces a valid group name and a non-empty member list (excluding the client user).
  *
  * @author Maximilian K&auml;fer
  * @since Envoy Client v0.1-beta
@@ -82,7 +82,7 @@ public class GroupCreationTab implements EventListener {
 				.map(User.class::cast)
 				.collect(Collectors.toList()));
 		resizeQuickSelectSpace(0);
-		quickSelectList.addEventFilter(MouseEvent.MOUSE_PRESSED, evt -> evt.consume());
+		quickSelectList.addEventFilter(MouseEvent.MOUSE_PRESSED, MouseEvent::consume);
 	}
 
 	/**
@@ -93,8 +93,10 @@ public class GroupCreationTab implements EventListener {
 	@FXML
 	private void userListClicked() {
 		if (userList.getSelectionModel().getSelectedItem() != null) {
-			quickSelectList.getItems().add(new QuickSelectControl(userList.getSelectionModel().getSelectedItem(), this::removeFromQuickSelection));
-			createButton.setDisable(quickSelectList.getItems().isEmpty() || groupNameField.getText().isBlank());
+			quickSelectList.getItems().add(new QuickSelectControl(
+				userList.getSelectionModel().getSelectedItem(), this::removeFromQuickSelection));
+			createButton.setDisable(
+				quickSelectList.getItems().isEmpty() || groupNameField.getText().isBlank());
 			resizeQuickSelectSpace(60);
 			userList.getItems().remove(userList.getSelectionModel().getSelectedItem());
 			userList.getSelectionModel().clearSelection();
@@ -102,13 +104,16 @@ public class GroupCreationTab implements EventListener {
 	}
 
 	/**
-	 * Checks, whether the {@code createButton} can be enabled because text is
-	 * present in the text field.
+	 * Checks, whether the {@code createButton} can be enabled because text is present in the text
+	 * field.
 	 *
 	 * @since Envoy Client v0.1-beta
 	 */
 	@FXML
-	private void textUpdated() { createButton.setDisable(quickSelectList.getItems().isEmpty() || groupNameField.getText().isBlank()); }
+	private void textUpdated() {
+		createButton
+			.setDisable(quickSelectList.getItems().isEmpty() || groupNameField.getText().isBlank());
+	}
 
 	/**
 	 * Sends a {@link GroupCreation} to the server and closes this scene.
@@ -152,24 +157,25 @@ public class GroupCreationTab implements EventListener {
 	private void createGroup(String name) {
 		Context.getInstance()
 			.getClient()
-			.send(new GroupCreation(name, quickSelectList.getItems().stream().map(q -> q.getUser().getID()).collect(Collectors.toSet())));
+			.send(new GroupCreation(name, quickSelectList.getItems().stream()
+				.map(q -> q.getUser().getID()).collect(Collectors.toSet())));
 	}
 
 	/**
-	 * Returns true if the proposed group name is already present in the users
-	 * {@code LocalDB}.
+	 * Returns true if the proposed group name is already present in the users {@code LocalDB}.
 	 *
 	 * @param newName the chosen group name
 	 * @return true if this name is already present
 	 * @since Envoy Client v0.1-beta
 	 */
 	public boolean groupNameAlreadyPresent(String newName) {
-		return localDB.getChats().stream().map(Chat::getRecipient).filter(Group.class::isInstance).map(Contact::getName).anyMatch(newName::equals);
+		return localDB.getChats().stream().map(Chat::getRecipient).filter(Group.class::isInstance)
+			.map(Contact::getName).anyMatch(newName::equals);
 	}
 
 	/**
 	 * Removes an element from the quickSelectList.
-	 * 
+	 *
 	 * @param element the element to be removed.
 	 * @since Envoy Client v0.3-beta
 	 */
@@ -234,11 +240,11 @@ public class GroupCreationTab implements EventListener {
 	}
 
 	@Event
-	private void onContactOperation(ContactOperation operation) {
-		if (operation.get() instanceof User) Platform.runLater(() -> {
+	private void onUserOperation(UserOperation operation) {
+		Platform.runLater(() -> {
 			switch (operation.getOperationType()) {
 				case ADD:
-					userList.getItems().add((User) operation.get());
+					userList.getItems().add(operation.get());
 					break;
 				case REMOVE:
 					userList.getItems().removeIf(operation.get()::equals);
diff --git a/client/src/main/java/envoy/client/ui/controller/LoginScene.java b/client/src/main/java/envoy/client/ui/controller/LoginScene.java
index 6176f8c..f9d062b 100644
--- a/client/src/main/java/envoy/client/ui/controller/LoginScene.java
+++ b/client/src/main/java/envoy/client/ui/controller/LoginScene.java
@@ -10,14 +10,15 @@ import javafx.scene.control.*;
 import javafx.scene.control.Alert.AlertType;
 import javafx.scene.image.ImageView;
 
-import envoy.client.data.ClientConfig;
-import envoy.client.ui.*;
-import envoy.client.util.IconUtil;
+import dev.kske.eventbus.*;
+
 import envoy.data.LoginCredentials;
 import envoy.event.HandshakeRejection;
 import envoy.util.*;
 
-import dev.kske.eventbus.*;
+import envoy.client.data.ClientConfig;
+import envoy.client.ui.Startup;
+import envoy.client.util.IconUtil;
 
 /**
  * Controller for the login scene.
@@ -78,25 +79,32 @@ public final class LoginScene implements EventListener {
 
 	@FXML
 	private void loginButtonPressed() {
-		final String user = userTextField.getText(), pass = passwordField.getText(), repeatPass = repeatPasswordField.getText();
+		final String	user			= userTextField.getText(), pass = passwordField.getText(),
+			repeatPass = repeatPasswordField.getText();
 		final boolean	requestToken	= cbStaySignedIn.isSelected();
 
 		// Prevent registration with unequal passwords
 		if (registration && !pass.equals(repeatPass)) {
-			new Alert(AlertType.ERROR, "The entered password is unequal to the repeated one").showAndWait();
+			new Alert(AlertType.ERROR, "The entered password is unequal to the repeated one")
+				.showAndWait();
 			repeatPasswordField.clear();
 		} else if (!Bounds.isValidContactName(user)) {
-			new Alert(AlertType.ERROR, "The entered user name is not valid (" + Bounds.CONTACT_NAME_PATTERN + ")").showAndWait();
+			new Alert(AlertType.ERROR,
+				"The entered user name is not valid (" + Bounds.CONTACT_NAME_PATTERN + ")")
+					.showAndWait();
 			userTextField.clear();
 		} else {
 			Instant lastSync = Startup.loadLastSync(userTextField.getText());
-			Startup.performHandshake(registration ? LoginCredentials.registration(user, pass, requestToken, Startup.VERSION, lastSync)
-					: LoginCredentials.login(user, pass, requestToken, Startup.VERSION, lastSync));
+			Startup.performHandshake(registration
+				? LoginCredentials.registration(user, pass, requestToken, Startup.VERSION, lastSync)
+				: LoginCredentials.login(user, pass, requestToken, Startup.VERSION, lastSync));
 		}
 	}
 
 	@FXML
-	private void offlineModeButtonPressed() { Startup.attemptOfflineMode(userTextField.getText()); }
+	private void offlineModeButtonPressed() {
+		Startup.attemptOfflineMode(userTextField.getText());
+	}
 
 	@FXML
 	private void registerSwitchPressed() {
@@ -127,5 +135,7 @@ public final class LoginScene implements EventListener {
 	}
 
 	@Event
-	private void onHandshakeRejection(HandshakeRejection evt) { Platform.runLater(() -> new Alert(AlertType.ERROR, evt.get()).showAndWait()); }
+	private void onHandshakeRejection(HandshakeRejection evt) {
+		Platform.runLater(() -> new Alert(AlertType.ERROR, evt.get()).showAndWait());
+	}
 }
diff --git a/client/src/main/java/envoy/client/ui/controller/SettingsScene.java b/client/src/main/java/envoy/client/ui/controller/SettingsScene.java
index 7a471e6..401ec3d 100644
--- a/client/src/main/java/envoy/client/ui/controller/SettingsScene.java
+++ b/client/src/main/java/envoy/client/ui/controller/SettingsScene.java
@@ -28,7 +28,8 @@ public final class SettingsScene implements KeyboardMapping {
 	@FXML
 	private void initialize() {
 		settingsList.setCellFactory(new ListCellFactory<>(pane -> new Label(pane.getTitle())));
-		settingsList.getItems().addAll(new GeneralSettingsPane(), new UserSettingsPane(), new DownloadSettingsPane(), new BugReportPane());
+		settingsList.getItems().addAll(new GeneralSettingsPane(), new UserSettingsPane(),
+			new DownloadSettingsPane(), new BugReportPane());
 	}
 
 	@FXML
@@ -41,10 +42,13 @@ public final class SettingsScene implements KeyboardMapping {
 	}
 
 	@FXML
-	private void backButtonClicked() { Context.getInstance().getSceneContext().pop(); }
+	private void backButtonClicked() {
+		Context.getInstance().getSceneContext().pop();
+	}
 
 	@Override
 	public Map<KeyCombination, Runnable> getKeyboardShortcuts() {
-		return Map.of(new KeyCodeCombination(KeyCode.B, KeyCombination.CONTROL_DOWN), this::backButtonClicked);
+		return Map.of(new KeyCodeCombination(KeyCode.B, KeyCombination.CONTROL_DOWN),
+			this::backButtonClicked);
 	}
 }
diff --git a/client/src/main/java/envoy/client/ui/listcell/AbstractListCell.java b/client/src/main/java/envoy/client/ui/listcell/AbstractListCell.java
index 1e12021..842f0fd 100644
--- a/client/src/main/java/envoy/client/ui/listcell/AbstractListCell.java
+++ b/client/src/main/java/envoy/client/ui/listcell/AbstractListCell.java
@@ -33,6 +33,7 @@ public abstract class AbstractListCell<T, U extends Node> extends ListCell<T> {
 			setGraphic(renderItem(item));
 		} else {
 			setGraphic(null);
+			setCursor(Cursor.DEFAULT);
 		}
 	}
 
diff --git a/client/src/main/java/envoy/client/ui/listcell/ChatListCell.java b/client/src/main/java/envoy/client/ui/listcell/ChatListCell.java
new file mode 100644
index 0000000..c4d3b46
--- /dev/null
+++ b/client/src/main/java/envoy/client/ui/listcell/ChatListCell.java
@@ -0,0 +1,55 @@
+package envoy.client.ui.listcell;
+
+import javafx.scene.control.*;
+
+import envoy.data.User;
+
+import envoy.client.data.*;
+import envoy.client.net.Client;
+import envoy.client.ui.control.ChatControl;
+import envoy.client.util.UserUtil;
+
+/**
+ * A list cell containing chats represented as chat controls.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Client v0.3-beta
+ */
+public class ChatListCell extends AbstractListCell<Chat, ChatControl> {
+
+	private static final Client client = Context.getInstance().getClient();
+
+	/**
+	 * @param listView the list view inside of which the cell will be displayed
+	 * @since Envoy Client v0.3-beta
+	 */
+	public ChatListCell(ListView<? extends Chat> listView) {
+		super(listView);
+	}
+
+	@Override
+	protected ChatControl renderItem(Chat chat) {
+		if (client.isOnline()) {
+			final var	menu		= new ContextMenu();
+			final var	removeMI	= new MenuItem();
+			removeMI.setText(
+				chat.isDisabled() ? "Delete "
+					: chat.getRecipient() instanceof User ? "Block "
+						: "Leave group " + chat.getRecipient().getName());
+			removeMI.setOnAction(
+				chat.isDisabled() ? e -> UserUtil.deleteContact(chat.getRecipient())
+					: e -> UserUtil.disableContact(chat.getRecipient()));
+			menu.getItems().add(removeMI);
+			setContextMenu(menu);
+		} else
+			setContextMenu(null);
+
+		// TODO: replace with icon in ChatControl
+		final var chatControl = new ChatControl(chat);
+		if (chat.isDisabled())
+			chatControl.getStyleClass().add("disabled-chat");
+		else
+			chatControl.getStyleClass().remove("disabled-chat");
+		return chatControl;
+	}
+}
diff --git a/client/src/main/java/envoy/client/ui/listcell/GenericListCell.java b/client/src/main/java/envoy/client/ui/listcell/GenericListCell.java
index 2959937..cc3784c 100644
--- a/client/src/main/java/envoy/client/ui/listcell/GenericListCell.java
+++ b/client/src/main/java/envoy/client/ui/listcell/GenericListCell.java
@@ -28,5 +28,7 @@ public final class GenericListCell<T, U extends Node> extends AbstractListCell<T
 	}
 
 	@Override
-	protected U renderItem(T item) { return renderer.apply(item); }
+	protected U renderItem(T item) {
+		return renderer.apply(item);
+	}
 }
diff --git a/client/src/main/java/envoy/client/ui/listcell/ListCellFactory.java b/client/src/main/java/envoy/client/ui/listcell/ListCellFactory.java
index faac35f..5c4d864 100644
--- a/client/src/main/java/envoy/client/ui/listcell/ListCellFactory.java
+++ b/client/src/main/java/envoy/client/ui/listcell/ListCellFactory.java
@@ -7,15 +7,15 @@ import javafx.scene.control.*;
 import javafx.util.Callback;
 
 /**
- * Provides a creation mechanism for generic list cells given a list view and a
- * conversion function.
+ * Provides a creation mechanism for generic list cells given a list view and a conversion function.
  *
  * @author Kai S. K. Engelbart
  * @param <T> the type of object to display
  * @param <U> the type of node displayed
  * @since Envoy Client v0.1-beta
  */
-public final class ListCellFactory<T, U extends Node> implements Callback<ListView<T>, ListCell<T>> {
+public final class ListCellFactory<T, U extends Node>
+	implements Callback<ListView<T>, ListCell<T>> {
 
 	private final Function<? super T, U> renderer;
 
@@ -23,8 +23,12 @@ public final class ListCellFactory<T, U extends Node> implements Callback<ListVi
 	 * @param renderer a function converting the type to display into a node
 	 * @since Envoy Client v0.1-beta
 	 */
-	public ListCellFactory(Function<? super T, U> renderer) { this.renderer = renderer; }
+	public ListCellFactory(Function<? super T, U> renderer) {
+		this.renderer = renderer;
+	}
 
 	@Override
-	public ListCell<T> call(ListView<T> listView) { return new GenericListCell<>(listView, renderer); }
+	public ListCell<T> call(ListView<T> listView) {
+		return new GenericListCell<>(listView, renderer);
+	}
 }
diff --git a/client/src/main/java/envoy/client/ui/listcell/MessageListCell.java b/client/src/main/java/envoy/client/ui/listcell/MessageListCell.java
index 49bcd61..75c1628 100644
--- a/client/src/main/java/envoy/client/ui/listcell/MessageListCell.java
+++ b/client/src/main/java/envoy/client/ui/listcell/MessageListCell.java
@@ -3,9 +3,10 @@ package envoy.client.ui.listcell;
 import javafx.geometry.*;
 import javafx.scene.control.ListView;
 
-import envoy.client.ui.control.MessageControl;
 import envoy.data.Message;
 
+import envoy.client.ui.control.MessageControl;
+
 /**
  * A list cell containing messages represented as message controls.
  *
@@ -18,15 +19,20 @@ public final class MessageListCell extends AbstractListCell<Message, MessageCont
 	 * @param listView the list view inside of which the cell will be displayed
 	 * @since Envoy Client v0.1-beta
 	 */
-	public MessageListCell(ListView<? extends Message> listView) { super(listView); }
+	public MessageListCell(ListView<? extends Message> listView) {
+		super(listView);
+	}
 
 	@Override
 	protected MessageControl renderItem(Message message) {
 		final var control = new MessageControl(message);
-		listView.widthProperty().addListener((observable, oldValue, newValue) -> adjustPadding(newValue.intValue(), control.isOwnMessage()));
+		listView.widthProperty().addListener((observable, oldValue,
+			newValue) -> adjustPadding(newValue.intValue(), control.isOwnMessage()));
 		adjustPadding((int) listView.getWidth(), control.isOwnMessage());
-		if (control.isOwnMessage()) setAlignment(Pos.CENTER_RIGHT);
-		else setAlignment(Pos.CENTER_LEFT);
+		if (control.isOwnMessage())
+			setAlignment(Pos.CENTER_RIGHT);
+		else
+			setAlignment(Pos.CENTER_LEFT);
 		return control;
 	}
 
diff --git a/client/src/main/java/envoy/client/ui/listcell/package-info.java b/client/src/main/java/envoy/client/ui/listcell/package-info.java
index dd5dd33..1cb7569 100644
--- a/client/src/main/java/envoy/client/ui/listcell/package-info.java
+++ b/client/src/main/java/envoy/client/ui/listcell/package-info.java
@@ -1,6 +1,5 @@
 /**
- * This package contains custom list cells that are used to display certain
- * things.
+ * This package contains custom list cells that are used to display certain things.
  *
  * @author Leon Hofmeister
  * @author Kai S. K. Engelbart
diff --git a/client/src/main/java/envoy/client/ui/settings/BugReportPane.java b/client/src/main/java/envoy/client/ui/settings/BugReportPane.java
index 0ac1d83..874fba8 100644
--- a/client/src/main/java/envoy/client/ui/settings/BugReportPane.java
+++ b/client/src/main/java/envoy/client/ui/settings/BugReportPane.java
@@ -7,8 +7,8 @@ import javafx.scene.input.InputEvent;
 import envoy.event.IssueProposal;
 
 /**
- * This class offers the option for users to submit a bug report. Only the title
- * of a bug is needed to be sent.
+ * This class offers the option for users to submit a bug report. Only the title of a bug is needed
+ * to be sent.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.2-beta
@@ -17,12 +17,15 @@ public final class BugReportPane extends OnlineOnlySettingsPane {
 
 	private final Label		titleLabel				= new Label("Suggest a title for the bug:");
 	private final TextField	titleTextField			= new TextField();
-	private final Label		pleaseExplainLabel		= new Label("Paste here the log of what went wrong and/ or explain what went wrong:");
+	private final Label		pleaseExplainLabel		=
+		new Label("Paste here the log of what went wrong and/ or explain what went wrong:");
 	private final TextArea	errorDetailArea			= new TextArea();
-	private final CheckBox	showUsernameInBugReport	= new CheckBox("Show your username in the bug report?");
+	private final CheckBox	showUsernameInBugReport	=
+		new CheckBox("Show your username in the bug report?");
 	private final Button	submitReportButton		= new Button("Submit report");
 
-	private final EventHandler<? super InputEvent> inputEventHandler = e -> submitReportButton.setDisable(titleTextField.getText().isBlank());
+	private final EventHandler<? super InputEvent> inputEventHandler =
+		e -> submitReportButton.setDisable(titleTextField.getText().isBlank());
 
 	/**
 	 * Creates a new {@code BugReportPane}.
@@ -59,7 +62,9 @@ public final class BugReportPane extends OnlineOnlySettingsPane {
 		submitReportButton.setDisable(true);
 		submitReportButton.setOnAction(e -> {
 			String title = titleTextField.getText(), description = errorDetailArea.getText();
-			client.send(showUsernameInBugReport.isSelected() ? new IssueProposal(title, description, true) : new IssueProposal(title, description, client.getSender().getName(), true));
+			client.send(
+				showUsernameInBugReport.isSelected() ? new IssueProposal(title, description, true)
+					: new IssueProposal(title, description, client.getSender().getName(), true));
 		});
 		getChildren().add(submitReportButton);
 	}
diff --git a/client/src/main/java/envoy/client/ui/settings/DownloadSettingsPane.java b/client/src/main/java/envoy/client/ui/settings/DownloadSettingsPane.java
index ae2f04f..2898b37 100644
--- a/client/src/main/java/envoy/client/ui/settings/DownloadSettingsPane.java
+++ b/client/src/main/java/envoy/client/ui/settings/DownloadSettingsPane.java
@@ -24,18 +24,22 @@ public final class DownloadSettingsPane extends SettingsPane {
 		setPadding(new Insets(15));
 
 		// Checkbox to disable asking
-		final var checkBox = new CheckBox(settings.getItems().get("autoSaveDownloads").getUserFriendlyName());
+		final var checkBox =
+			new CheckBox(settings.getItems().get("autoSaveDownloads").getUserFriendlyName());
 		checkBox.setSelected(settings.isDownloadSavedWithoutAsking());
-		checkBox.setTooltip(new Tooltip("Determines whether a \"Select save location\" - dialogue will be shown when saving attachments."));
+		checkBox.setTooltip(new Tooltip(
+			"Determines whether a \"Select save location\" - dialogue will be shown when saving attachments."));
 		checkBox.setOnAction(e -> settings.setDownloadSavedWithoutAsking(checkBox.isSelected()));
 		getChildren().add(checkBox);
 
 		// Displaying the default path to save to
-		final var pathLabel = new Label(settings.getItems().get("downloadLocation").getDescription() + ":");
+		final var pathLabel =
+			new Label(settings.getItems().get("downloadLocation").getDescription() + ":");
 		pathLabel.setWrapText(true);
 		getChildren().add(pathLabel);
 		final var hbox = new HBox(20);
-		Tooltip.install(hbox, new Tooltip("Determines the location where attachments will be saved to."));
+		Tooltip.install(hbox,
+			new Tooltip("Determines the location where attachments will be saved to."));
 		final var currentPath = new Label(settings.getDownloadLocation().getAbsolutePath());
 		hbox.getChildren().add(currentPath);
 
@@ -45,7 +49,8 @@ public final class DownloadSettingsPane extends SettingsPane {
 			final var directoryChooser = new DirectoryChooser();
 			directoryChooser.setTitle("Select the directory where attachments should be saved to");
 			directoryChooser.setInitialDirectory(settings.getDownloadLocation());
-			final var selectedDirectory = directoryChooser.showDialog(context.getSceneContext().getStage());
+			final var selectedDirectory =
+				directoryChooser.showDialog(context.getSceneContext().getStage());
 
 			if (selectedDirectory != null) {
 				currentPath.setText(selectedDirectory.getAbsolutePath());
diff --git a/client/src/main/java/envoy/client/ui/settings/GeneralSettingsPane.java b/client/src/main/java/envoy/client/ui/settings/GeneralSettingsPane.java
index bed9af9..3f773fc 100644
--- a/client/src/main/java/envoy/client/ui/settings/GeneralSettingsPane.java
+++ b/client/src/main/java/envoy/client/ui/settings/GeneralSettingsPane.java
@@ -2,13 +2,14 @@ package envoy.client.ui.settings;
 
 import javafx.scene.control.*;
 
+import dev.kske.eventbus.EventBus;
+
+import envoy.data.User.UserStatus;
+
 import envoy.client.data.SettingsItem;
 import envoy.client.event.ThemeChangeEvent;
 import envoy.client.ui.StatusTrayIcon;
 import envoy.client.util.UserUtil;
-import envoy.data.User.UserStatus;
-
-import dev.kske.eventbus.EventBus;
 
 /**
  * @author Kai S. K. Engelbart
@@ -27,22 +28,27 @@ public final class GeneralSettingsPane extends SettingsPane {
 
 		// Add hide on close if supported
 		if (StatusTrayIcon.isSupported()) {
-			final var	hideOnCloseCheckbox	= new SettingsCheckbox((SettingsItem<Boolean>) settingsItems.get("hideOnClose"));
-			final var	hideOnCloseTooltip	= new Tooltip("If selected, Envoy will still be present in the task bar when closed.");
+			final var	hideOnCloseCheckbox	=
+				new SettingsCheckbox((SettingsItem<Boolean>) settingsItems.get("hideOnClose"));
+			final var	hideOnCloseTooltip	= new Tooltip(
+				"If selected, Envoy will still be present in the task bar when closed.");
 			hideOnCloseTooltip.setWrapText(true);
 			hideOnCloseCheckbox.setTooltip(hideOnCloseTooltip);
 			getChildren().add(hideOnCloseCheckbox);
 		}
 
-		final var	enterToSendCheckbox	= new SettingsCheckbox((SettingsItem<Boolean>) settingsItems.get("enterToSend"));
+		final var	enterToSendCheckbox	=
+			new SettingsCheckbox((SettingsItem<Boolean>) settingsItems.get("enterToSend"));
 		final var	enterToSendTooltip	= new Tooltip(
-				"When selected, messages can be sent pressing \"Enter\". A line break can be inserted by pressing \"Ctrl\" + \"Enter\". Else it will be the other way around.");
+			"When selected, messages can be sent pressing \"Enter\". A line break can be inserted by pressing \"Ctrl\" + \"Enter\". Else it will be the other way around.");
 		enterToSendTooltip.setWrapText(true);
 		enterToSendCheckbox.setTooltip(enterToSendTooltip);
 		getChildren().add(enterToSendCheckbox);
 
-		final var	askForConfirmationCheckbox	= new SettingsCheckbox((SettingsItem<Boolean>) settingsItems.get("askForConfirmation"));
-		final var	askForConfirmationTooltip	= new Tooltip("When selected, nothing will prompt a confirmation dialog");
+		final var	askForConfirmationCheckbox	=
+			new SettingsCheckbox((SettingsItem<Boolean>) settingsItems.get("askForConfirmation"));
+		final var	askForConfirmationTooltip	=
+			new Tooltip("When selected, nothing will prompt a confirmation dialog");
 		askForConfirmationTooltip.setWrapText(true);
 		askForConfirmationCheckbox.setTooltip(askForConfirmationTooltip);
 		getChildren().add(askForConfirmationCheckbox);
@@ -50,9 +56,13 @@ public final class GeneralSettingsPane extends SettingsPane {
 		final var combobox = new ComboBox<String>();
 		combobox.getItems().add("dark");
 		combobox.getItems().add("light");
-		combobox.setTooltip(new Tooltip("Determines the current theme Envoy will be displayed in."));
+		combobox
+			.setTooltip(new Tooltip("Determines the current theme Envoy will be displayed in."));
 		combobox.setValue(settings.getCurrentTheme());
-		combobox.setOnAction(e -> { settings.setCurrentTheme(combobox.getValue()); EventBus.getInstance().dispatch(new ThemeChangeEvent()); });
+		combobox.setOnAction(e -> {
+			settings.setCurrentTheme(combobox.getValue());
+			EventBus.getInstance().dispatch(new ThemeChangeEvent());
+		});
 		getChildren().add(combobox);
 
 		final var statusComboBox = new ComboBox<UserStatus>();
@@ -64,7 +74,8 @@ public final class GeneralSettingsPane extends SettingsPane {
 
 		final var logoutButton = new Button("Logout");
 		logoutButton.setOnAction(e -> UserUtil.logout());
-		final var logoutTooltip = new Tooltip("Brings you back to the login screen and removes \"remember me\" status from this account");
+		final var logoutTooltip = new Tooltip(
+			"Brings you back to the login screen and removes \"remember me\" status from this account");
 		logoutTooltip.setWrapText(true);
 		logoutButton.setTooltip(logoutTooltip);
 		getChildren().add(logoutButton);
diff --git a/client/src/main/java/envoy/client/ui/settings/OnlineOnlySettingsPane.java b/client/src/main/java/envoy/client/ui/settings/OnlineOnlySettingsPane.java
index 5ba18b4..3d70fc6 100644
--- a/client/src/main/java/envoy/client/ui/settings/OnlineOnlySettingsPane.java
+++ b/client/src/main/java/envoy/client/ui/settings/OnlineOnlySettingsPane.java
@@ -8,10 +8,10 @@ import javafx.scene.paint.Color;
 import envoy.client.net.Client;
 
 /**
- * Inheriting from this class signifies that options should only be available if
- * the {@link envoy.data.User} is currently online. If the user is currently
- * offline, all {@link javafx.scene.Node} variables will be disabled and a
- * {@link Tooltip} will be displayed for the whole node.
+ * Inheriting from this class signifies that options should only be available if the
+ * {@link envoy.data.User} is currently online. If the user is currently offline, all
+ * {@link javafx.scene.Node} variables will be disabled and a {@link Tooltip} will be displayed for
+ * the whole node.
  *
  * @author Leon Hofmeister
  * @author Kai S. K. Engelbart
@@ -21,7 +21,8 @@ public abstract class OnlineOnlySettingsPane extends SettingsPane {
 
 	protected final Client client = context.getClient();
 
-	private final Tooltip beOnlineReminder = new Tooltip("You need to be online to modify your account.");
+	private final Tooltip beOnlineReminder =
+		new Tooltip("You need to be online to modify your account.");
 
 	/**
 	 * @param title the title of this pane
@@ -33,14 +34,17 @@ public abstract class OnlineOnlySettingsPane extends SettingsPane {
 		setDisable(!client.isOnline());
 
 		if (!client.isOnline()) {
-			final var infoLabel = new Label("You shall not pass!\n(... Unless you would happen to be online)");
+			final var infoLabel =
+				new Label("You shall not pass!\n(... Unless you would happen to be online)");
 			infoLabel.setId("info-label-warning");
 			infoLabel.setWrapText(true);
 			getChildren().add(infoLabel);
-			setBackground(new Background(new BackgroundFill(Color.grayRgb(100, 0.3), CornerRadii.EMPTY, Insets.EMPTY)));
+			setBackground(new Background(
+				new BackgroundFill(Color.grayRgb(100, 0.3), CornerRadii.EMPTY, Insets.EMPTY)));
 
 			Tooltip.install(this, beOnlineReminder);
-		} else Tooltip.uninstall(this, beOnlineReminder);
+		} else
+			Tooltip.uninstall(this, beOnlineReminder);
 	}
 
 	/**
@@ -49,5 +53,7 @@ public abstract class OnlineOnlySettingsPane extends SettingsPane {
 	 * @param text the text to display
 	 * @since Envoy Client v0.2-beta
 	 */
-	protected void setToolTipText(String text) { beOnlineReminder.setText(text); }
+	protected void setToolTipText(String text) {
+		beOnlineReminder.setText(text);
+	}
 }
diff --git a/client/src/main/java/envoy/client/ui/settings/SettingsCheckbox.java b/client/src/main/java/envoy/client/ui/settings/SettingsCheckbox.java
index b171d07..5850328 100644
--- a/client/src/main/java/envoy/client/ui/settings/SettingsCheckbox.java
+++ b/client/src/main/java/envoy/client/ui/settings/SettingsCheckbox.java
@@ -20,9 +20,9 @@ public final class SettingsCheckbox extends CheckBox {
 	public SettingsCheckbox(SettingsItem<Boolean> settingsItem) {
 		super(settingsItem.getUserFriendlyName());
 		setSelected(settingsItem.get());
-		
+
 		// "Schau, es hat sich behindert" - Kai, 2020
-		
+
 		addEventHandler(ActionEvent.ACTION, e -> settingsItem.set(isSelected()));
 	}
 }
diff --git a/client/src/main/java/envoy/client/ui/settings/SettingsPane.java b/client/src/main/java/envoy/client/ui/settings/SettingsPane.java
index ed80f20..7adf76c 100644
--- a/client/src/main/java/envoy/client/ui/settings/SettingsPane.java
+++ b/client/src/main/java/envoy/client/ui/settings/SettingsPane.java
@@ -15,7 +15,9 @@ public abstract class SettingsPane extends VBox {
 	protected static final Settings	settings	= Settings.getInstance();
 	protected static final Context	context		= Context.getInstance();
 
-	protected SettingsPane(String title) { this.title = title; }
+	protected SettingsPane(String title) {
+		this.title = title;
+	}
 
 	/**
 	 * @return the title of this settings pane
diff --git a/client/src/main/java/envoy/client/ui/settings/UserSettingsPane.java b/client/src/main/java/envoy/client/ui/settings/UserSettingsPane.java
index fdf751e..75a97d1 100644
--- a/client/src/main/java/envoy/client/ui/settings/UserSettingsPane.java
+++ b/client/src/main/java/envoy/client/ui/settings/UserSettingsPane.java
@@ -14,12 +14,13 @@ import javafx.scene.input.InputEvent;
 import javafx.scene.layout.HBox;
 import javafx.stage.FileChooser;
 
-import envoy.client.ui.control.ProfilePicImageView;
-import envoy.client.util.IconUtil;
+import dev.kske.eventbus.EventBus;
+
 import envoy.event.*;
 import envoy.util.*;
 
-import dev.kske.eventbus.EventBus;
+import envoy.client.ui.control.ProfilePicImageView;
+import envoy.client.util.IconUtil;
 
 /**
  * @author Leon Hofmeister
@@ -58,12 +59,14 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 		profilePic.setFitWidth(60);
 		profilePic.setFitHeight(60);
 		profilePic.setOnMouseClicked(e -> {
-			if (!client.isOnline()) return;
+			if (!client.isOnline())
+				return;
 			final var pictureChooser = new FileChooser();
 
 			pictureChooser.setTitle("Select a new profile pic");
 			pictureChooser.setInitialDirectory(new File(System.getProperty("user.home")));
-			pictureChooser.getExtensionFilters().add(new FileChooser.ExtensionFilter("Pictures", "*.png", "*.jpg", "*.bmp", "*.gif"));
+			pictureChooser.getExtensionFilters().add(
+				new FileChooser.ExtensionFilter("Pictures", "*.png", "*.jpg", "*.bmp", "*.gif"));
 
 			final var file = pictureChooser.showOpenDialog(context.getSceneContext().getStage());
 
@@ -72,7 +75,8 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 				// Check max file size
 				// TODO: Move to config
 				if (file.length() > 5E6) {
-					new Alert(AlertType.WARNING, "The selected file exceeds the size limit of 5MB!").showAndWait();
+					new Alert(AlertType.WARNING, "The selected file exceeds the size limit of 5MB!")
+						.showAndWait();
 					return;
 				}
 
@@ -92,8 +96,8 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 		newUsername = username;
 		usernameTextField.setText(username);
 		final EventHandler<? super InputEvent> textChanged = e -> {
-			newUsername = usernameTextField.getText();
-			usernameChanged = newUsername != username;
+			newUsername		= usernameTextField.getText();
+			usernameChanged	= newUsername != username;
 		};
 		usernameTextField.setOnInputMethodTextChanged(textChanged);
 		usernameTextField.setOnKeyTyped(textChanged);
@@ -102,14 +106,21 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 
 		// "Displaying" the password change mechanism
 		final HBox[]	passwordHBoxes	= { new HBox(), new HBox(), new HBox() };
-		final Label[]	passwordLabels	= { new Label("Enter current password:"), new Label("Enter new password:"),
+		final Label[]	passwordLabels	=
+			{	new Label("Enter current password:"), new Label("Enter new password:"),
 				new Label("Repeat new password:") };
 
-		final PasswordField[]					passwordFields	= { currentPasswordField, newPasswordField, repeatNewPasswordField };
+		final PasswordField[]					passwordFields	=
+			{ currentPasswordField, newPasswordField, repeatNewPasswordField };
 		final EventHandler<? super InputEvent>	passwordEntered	= e -> {
-																	newPassword		= newPasswordField.getText();
-																	validPassword	= newPassword.equals(repeatNewPasswordField.getText())
-																			&& !newPasswordField.getText().isBlank();
+																	newPassword		=
+																		newPasswordField.getText();
+																	validPassword	= newPassword
+																		.equals(
+																			repeatNewPasswordField
+																				.getText())
+																		&& !newPasswordField
+																			.getText().isBlank();
 																};
 		newPasswordField.setOnInputMethodTextChanged(passwordEntered);
 		newPasswordField.setOnKeyTyped(passwordEntered);
@@ -125,7 +136,8 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 		}
 
 		// Displaying the save button
-		saveButton.setOnAction(e -> save(client.getSender().getID(), currentPasswordField.getText()));
+		saveButton
+			.setOnAction(e -> save(client.getSender().getID(), currentPasswordField.getText()));
 		saveButton.setAlignment(Pos.BOTTOM_RIGHT);
 		getChildren().add(saveButton);
 	}
@@ -156,7 +168,9 @@ public final class UserSettingsPane extends OnlineOnlySettingsPane {
 		} else if (!validContactName) {
 			final var alert = new Alert(AlertType.ERROR);
 			alert.setTitle("Invalid username");
-			alert.setContentText("The entered username does not conform with the naming limitations: " + Bounds.CONTACT_NAME_PATTERN);
+			alert.setContentText(
+				"The entered username does not conform with the naming limitations: "
+					+ Bounds.CONTACT_NAME_PATTERN);
 			alert.showAndWait();
 			logger.log(Level.INFO, "An invalid username was requested.");
 			return;
diff --git a/client/src/main/java/envoy/client/ui/settings/package-info.java b/client/src/main/java/envoy/client/ui/settings/package-info.java
index ea3fdb6..c918d1e 100644
--- a/client/src/main/java/envoy/client/ui/settings/package-info.java
+++ b/client/src/main/java/envoy/client/ui/settings/package-info.java
@@ -1,6 +1,5 @@
 /**
- * This package contains classes used for representing the settings
- * visually.
+ * This package contains classes used for representing the settings visually.
  *
  * @author Leon Hofmeister
  * @author Kai S. K. Engelbart
diff --git a/client/src/main/java/envoy/client/util/IconUtil.java b/client/src/main/java/envoy/client/util/IconUtil.java
index 3445b42..6aa2509 100644
--- a/client/src/main/java/envoy/client/util/IconUtil.java
+++ b/client/src/main/java/envoy/client/util/IconUtil.java
@@ -9,12 +9,12 @@ import javax.imageio.ImageIO;
 
 import javafx.scene.image.Image;
 
-import envoy.client.data.Settings;
 import envoy.util.EnvoyLog;
 
+import envoy.client.data.Settings;
+
 /**
- * Provides static utility methods for loading icons from the resource
- * folder.
+ * Provides static utility methods for loading icons from the resource folder.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Client v0.1-beta
@@ -34,7 +34,10 @@ public final class IconUtil {
 	 * @return the loaded image
 	 * @since Envoy Client v0.1-beta
 	 */
-	public static Image load(String path) { return cache.computeIfAbsent(path, p -> new Image(IconUtil.class.getResource(p).toExternalForm())); }
+	public static Image load(String path) {
+		return cache.computeIfAbsent(path,
+			p -> new Image(IconUtil.class.getResource(p).toExternalForm()));
+	}
 
 	/**
 	 * Loads an image from the resource folder and scales it to the given size.
@@ -45,12 +48,13 @@ public final class IconUtil {
 	 * @since Envoy Client v0.1-beta
 	 */
 	public static Image load(String path, int size) {
-		return scaledCache.computeIfAbsent(path + size, p -> new Image(IconUtil.class.getResource(path).toExternalForm(), size, size, true, true));
+		return scaledCache.computeIfAbsent(path + size,
+			p -> new Image(IconUtil.class.getResource(path).toExternalForm(), size, size, true,
+				true));
 	}
 
 	/**
-	 * Loads a {@code .png} image from the sub-folder {@code /icons/} of the
-	 * resource folder.
+	 * Loads a {@code .png} image from the sub-folder {@code /icons/} of the resource folder.
 	 * <p>
 	 * The suffix {@code .png} is automatically appended.
 	 *
@@ -60,11 +64,13 @@ public final class IconUtil {
 	 * @apiNote let's load a sample image {@code /icons/abc.png}.<br>
 	 *          To do that, we only have to call {@code IconUtil.loadIcon("abc")}
 	 */
-	public static Image loadIcon(String name) { return load("/icons/" + name + ".png"); }
+	public static Image loadIcon(String name) {
+		return load("/icons/" + name + ".png");
+	}
 
 	/**
-	 * Loads a {@code .png} image from the sub-folder {@code /icons/} of the
-	 * resource folder and scales it to the given size.<br>
+	 * Loads a {@code .png} image from the sub-folder {@code /icons/} of the resource folder and
+	 * scales it to the given size.<br>
 	 * The suffix {@code .png} is automatically appended.
 	 *
 	 * @param name the image name without the .png suffix
@@ -72,20 +78,19 @@ public final class IconUtil {
 	 * @return the loaded image
 	 * @since Envoy Client v0.1-beta
 	 * @apiNote let's load a sample image {@code /icons/abc.png} in size 16.<br>
-	 *          To do that, we only have to call
-	 *          {@code IconUtil.loadIcon("abc", 16)}
+	 *          To do that, we only have to call {@code IconUtil.loadIcon("abc", 16)}
 	 */
-	public static Image loadIcon(String name, int size) { return load("/icons/" + name + ".png", size); }
+	public static Image loadIcon(String name, int size) {
+		return load("/icons/" + name + ".png", size);
+	}
 
 	/**
-	 * Loads a {@code .png} image whose design depends on the currently active theme
-	 * from the sub-folder {@code /icons/dark/} or {@code /icons/light/} of the
-	 * resource folder.
+	 * Loads a {@code .png} image whose design depends on the currently active theme from the
+	 * sub-folder {@code /icons/dark/} or {@code /icons/light/} of the resource folder.
 	 * <p>
 	 * The suffix {@code .png} is automatically appended.
 	 *
-	 * @param name the image name without the "black" or "white" suffix and without
-	 *             the .png suffix
+	 * @param name the image name without the "black" or "white" suffix and without the .png suffix
 	 * @return the loaded image
 	 * @since Envoy Client v0.1-beta
 	 * @apiNote let's take two sample images {@code /icons/dark/abc.png} and
@@ -93,12 +98,14 @@ public final class IconUtil {
 	 *          To do that theme sensitive, we only have to call
 	 *          {@code IconUtil.loadIconThemeSensitive("abc")}
 	 */
-	public static Image loadIconThemeSensitive(String name) { return loadIcon(themeSpecificSubFolder() + name); }
+	public static Image loadIconThemeSensitive(String name) {
+		return loadIcon(themeSpecificSubFolder() + name);
+	}
 
 	/**
-	 * Loads a {@code .png} image whose design depends on the currently active theme
-	 * from the sub-folder {@code /icons/dark/} or {@code /icons/light/} of the
-	 * resource folder and scales it to the given size.
+	 * Loads a {@code .png} image whose design depends on the currently active theme from the
+	 * sub-folder {@code /icons/dark/} or {@code /icons/light/} of the resource folder and scales it
+	 * to the given size.
 	 * <p>
 	 * The suffix {@code .png} is automatically appended.
 	 *
@@ -111,20 +118,19 @@ public final class IconUtil {
 	 *          To do that theme sensitive, we only have to call
 	 *          {@code IconUtil.loadIconThemeSensitive("abc", 16)}
 	 */
-	public static Image loadIconThemeSensitive(String name, int size) { return loadIcon(themeSpecificSubFolder() + name, size); }
+	public static Image loadIconThemeSensitive(String name, int size) {
+		return loadIcon(themeSpecificSubFolder() + name, size);
+	}
 
 	/**
-	 *
-	 * Loads images specified by an enum. The images have to be named like the
-	 * lowercase enum constants with {@code .png} extension and be located inside a
-	 * folder with the lowercase name of the enum, which must be contained inside
-	 * the {@code /icons/} folder.
+	 * Loads images specified by an enum. The images have to be named like the lowercase enum
+	 * constants with {@code .png} extension and be located inside a folder with the lowercase name
+	 * of the enum, which must be contained inside the {@code /icons/} folder.
 	 *
 	 * @param <T>       the enum that specifies the images to load
 	 * @param enumClass the class of the enum
 	 * @param size      the size to scale the images to
-	 * @return a map containing the loaded images with the corresponding enum
-	 *         constants as keys
+	 * @return a map containing the loaded images with the corresponding enum constants as keys
 	 * @since Envoy Client v0.1-beta
 	 */
 	public static <T extends Enum<T>> EnumMap<T, Image> loadByEnum(Class<T> enumClass, int size) {
@@ -147,22 +153,25 @@ public final class IconUtil {
 			try {
 				return ImageIO.read(IconUtil.class.getResource(path));
 			} catch (IOException e) {
-				EnvoyLog.getLogger(IconUtil.class).log(Level.WARNING, String.format("Could not load image at path %s: ", path), e);
+				EnvoyLog.getLogger(IconUtil.class).log(Level.WARNING,
+					String.format("Could not load image at path %s: ", path), e);
 				return null;
 			}
 		});
 	}
 
 	/**
-	 * This method should be called if the display of an image depends upon the
-	 * currently active theme.<br>
-	 * In case of a default theme, the string returned will be
-	 * ({@code dark/} or {@code light/}), otherwise it will be empty.
+	 * This method should be called if the display of an image depends upon the currently active
+	 * theme.<br>
+	 * In case of a default theme, the string returned will be ({@code dark/} or {@code light/}),
+	 * otherwise it will be empty.
 	 *
 	 * @return the theme specific folder
 	 * @since Envoy Client v0.1-beta
 	 */
 	private static String themeSpecificSubFolder() {
-		return Settings.getInstance().isUsingDefaultTheme() ? Settings.getInstance().getCurrentTheme() + "/" : "";
+		return Settings.getInstance().isUsingDefaultTheme()
+			? Settings.getInstance().getCurrentTheme() + "/"
+			: "";
 	}
 }
diff --git a/client/src/main/java/envoy/client/util/MessageUtil.java b/client/src/main/java/envoy/client/util/MessageUtil.java
index 468e8dc..dc73a53 100644
--- a/client/src/main/java/envoy/client/util/MessageUtil.java
+++ b/client/src/main/java/envoy/client/util/MessageUtil.java
@@ -7,13 +7,14 @@ import java.util.logging.*;
 
 import javafx.stage.FileChooser;
 
-import envoy.client.data.*;
-import envoy.client.event.MessageDeletion;
-import envoy.client.ui.controller.ChatScene;
+import dev.kske.eventbus.EventBus;
+
 import envoy.data.Message;
 import envoy.util.EnvoyLog;
 
-import dev.kske.eventbus.EventBus;
+import envoy.client.data.*;
+import envoy.client.event.MessageDeletion;
+import envoy.client.ui.controller.ChatScene;
 
 /**
  * Contains methods that are commonly used for {@link Message}s.
@@ -34,8 +35,10 @@ public class MessageUtil {
 	 * @since Envoy Client v0.3-beta
 	 */
 	public static void copyMessageText(Message message) {
-		logger.log(Level.FINEST, "A copy of message text \"" + message.getText() + "\" was requested");
-		Toolkit.getDefaultToolkit().getSystemClipboard().setContents(new StringSelection(message.getText()), null);
+		logger.log(Level.FINEST,
+			"A copy of message text \"" + message.getText() + "\" was requested");
+		Toolkit.getDefaultToolkit().getSystemClipboard()
+			.setContents(new StringSelection(message.getText()), null);
 	}
 
 	/**
@@ -46,8 +49,10 @@ public class MessageUtil {
 	 */
 	public static void deleteMessage(Message message) {
 		final var	messageDeletionEvent	= new MessageDeletion(message.getID());
-		final var	controller				= Context.getInstance().getSceneContext().getController();
-		if (controller instanceof ChatScene) ((ChatScene) controller).clearMessageSelection();
+		final var	controller				=
+			Context.getInstance().getSceneContext().getController();
+		if (controller instanceof ChatScene)
+			((ChatScene) controller).clearMessageSelection();
 
 		// Removing the message locally
 		EventBus.getInstance().dispatch(messageDeletionEvent);
@@ -56,22 +61,24 @@ public class MessageUtil {
 	}
 
 	/**
-	 * Forwards the given message.
-	 * Currently not implemented.
+	 * Forwards the given message. Currently not implemented.
 	 *
 	 * @param message the message to forward
 	 * @since Envoy Client v0.3-beta
 	 */
-	public static void forwardMessage(Message message) { logger.log(Level.FINEST, "Message forwarding was requested for " + message); }
+	public static void forwardMessage(Message message) {
+		logger.log(Level.FINEST, "Message forwarding was requested for " + message);
+	}
 
 	/**
-	 * Quotes the given message.
-	 * Currently not implemented.
+	 * Quotes the given message. Currently not implemented.
 	 *
 	 * @param message the message to quote
 	 * @since Envoy Client v0.3-beta
 	 */
-	public static void quoteMessage(Message message) { logger.log(Level.FINEST, "Message quotation was requested for " + message); }
+	public static void quoteMessage(Message message) {
+		logger.log(Level.FINEST, "Message quotation was requested for " + message);
+	}
 
 	/**
 	 * Saves the attachment of a message, if present.
@@ -81,7 +88,8 @@ public class MessageUtil {
 	 * @since Envoy Client v0.3-beta
 	 */
 	public static void saveAttachment(Message message) {
-		if (!message.hasAttachment()) throw new IllegalArgumentException("Cannot save a non-existing attachment");
+		if (!message.hasAttachment())
+			throw new IllegalArgumentException("Cannot save a non-existing attachment");
 		File		file;
 		final var	fileName			= message.getAttachment().getName();
 		final var	downloadLocation	= Settings.getInstance().getDownloadLocation();
@@ -92,14 +100,17 @@ public class MessageUtil {
 			fileChooser.setInitialFileName(fileName);
 			fileChooser.setInitialDirectory(downloadLocation);
 			file = fileChooser.showSaveDialog(Context.getInstance().getSceneContext().getStage());
-		} else file = new File(downloadLocation, fileName);
+		} else
+			file = new File(downloadLocation, fileName);
 
 		// A file was selected
-		if (file != null) try (var fos = new FileOutputStream(file)) {
-			fos.write(message.getAttachment().getData());
-			logger.log(Level.FINE, "Attachment of message was saved at " + file.getAbsolutePath());
-		} catch (final IOException e) {
-			logger.log(Level.WARNING, "Could not save attachment of " + message + ": ", e);
-		}
+		if (file != null)
+			try (var fos = new FileOutputStream(file)) {
+				fos.write(message.getAttachment().getData());
+				logger.log(Level.FINE,
+					"Attachment of message was saved at " + file.getAbsolutePath());
+			} catch (final IOException e) {
+				logger.log(Level.WARNING, "Could not save attachment of " + message + ": ", e);
+			}
 	}
 }
diff --git a/client/src/main/java/envoy/client/util/ReflectionUtil.java b/client/src/main/java/envoy/client/util/ReflectionUtil.java
index 49273f8..468bf17 100644
--- a/client/src/main/java/envoy/client/util/ReflectionUtil.java
+++ b/client/src/main/java/envoy/client/util/ReflectionUtil.java
@@ -14,47 +14,43 @@ public final class ReflectionUtil {
 	private ReflectionUtil() {}
 
 	/**
-	 * Gets all declared variable values of the given instance that have the
-	 * specified class.
+	 * Gets all declared variable values of the given instance that have the specified class.
 	 * <p>
-	 * (i.e. can get all {@code JComponents} (Swing) or {@code Nodes} (JavaFX) in a
-	 * GUI class).
+	 * (i.e. can get all {@code JComponents} (Swing) or {@code Nodes} (JavaFX) in a GUI class).
 	 * <p>
 	 * <b>Important: If you are using a module, you first need to declare <br>
 	 * "opens {your_package} to envoy.client.util;" in your module-info.java</b>.
 	 *
 	 * @param <T>          the type of the object
 	 * @param <R>          the type to return
-	 * @param instance     the instance of a given class whose values are to be
-	 *                     evaluated
+	 * @param instance     the instance of a given class whose values are to be evaluated
 	 * @param typeToReturn the type of variable to return
 	 * @return all variables in the given instance that have the requested type
 	 * @throws RuntimeException if an exception occurs
 	 * @since Envoy Client v0.2-beta
 	 */
-	public static <T, R> Stream<R> getAllDeclaredVariablesOfTypeAsStream(T instance, Class<R> typeToReturn) {
-		return Arrays.stream(instance.getClass().getDeclaredFields()).filter(field -> typeToReturn.isAssignableFrom(field.getType())).map(field -> {
-			try {
-				field.setAccessible(true);
-				return typeToReturn.cast(field.get(instance));
-			} catch (IllegalArgumentException | IllegalAccessException e) {
-				throw new RuntimeException(e);
-			}
-		});
+	public static <T, R> Stream<R> getAllDeclaredVariablesOfTypeAsStream(T instance,
+		Class<R> typeToReturn) {
+		return Arrays.stream(instance.getClass().getDeclaredFields())
+			.filter(field -> typeToReturn.isAssignableFrom(field.getType())).map(field -> {
+				try {
+					field.setAccessible(true);
+					return typeToReturn.cast(field.get(instance));
+				} catch (IllegalArgumentException | IllegalAccessException e) {
+					throw new RuntimeException(e);
+				}
+			});
 	}
 
 	/**
-	 * Gets all declared variables of the given instance that are children of
-	 * {@code Node}.
+	 * Gets all declared variables of the given instance that are children of {@code Node}.
 	 * <p>
 	 * <b>Important: If you are using a module, you first need to declare <br>
 	 * "opens {your_package} to envoy.client.util;" in your module-info.java</b>.
 	 *
 	 * @param <T>      the type of the instance
-	 * @param instance the instance of a given class whose values are to be
-	 *                 evaluated
-	 * @return all variables of the given object that have the requested type as
-	 *         {@code Stream}
+	 * @param instance the instance of a given class whose values are to be evaluated
+	 * @return all variables of the given object that have the requested type as {@code Stream}
 	 * @since Envoy Client v0.2-beta
 	 */
 	public static <T> Stream<Node> getAllDeclaredNodeVariablesAsStream(T instance) {
@@ -62,15 +58,13 @@ public final class ReflectionUtil {
 	}
 
 	/**
-	 * Gets all declared variables of the given instance that are children of
-	 * {@code Node}<br>
+	 * Gets all declared variables of the given instance that are children of {@code Node}<br>
 	 * <p>
 	 * <b>Important: If you are using a module, you first need to declare <br>
 	 * "opens {your_package} to envoy.client.util;" in your module-info.java</b>.
 	 *
 	 * @param <T>      the type of the instance
-	 * @param instance the instance of a given class whose values are to be
-	 *                 evaluated
+	 * @param instance the instance of a given class whose values are to be evaluated
 	 * @return all variables of the given object that have the requested type
 	 * @since Envoy Client v0.2-beta
 	 */
diff --git a/client/src/main/java/envoy/client/util/UserUtil.java b/client/src/main/java/envoy/client/util/UserUtil.java
index 4f1b37b..27078cc 100644
--- a/client/src/main/java/envoy/client/util/UserUtil.java
+++ b/client/src/main/java/envoy/client/util/UserUtil.java
@@ -1,19 +1,23 @@
 package envoy.client.util;
 
-import java.util.logging.Level;
+import java.util.logging.*;
 
 import javafx.scene.control.Alert;
 import javafx.scene.control.Alert.AlertType;
 
+import dev.kske.eventbus.EventBus;
+
+import envoy.data.*;
+import envoy.data.User.UserStatus;
+import envoy.event.*;
+import envoy.event.contact.UserOperation;
+import envoy.util.EnvoyLog;
+
 import envoy.client.data.Context;
 import envoy.client.event.*;
 import envoy.client.helper.*;
 import envoy.client.ui.SceneContext.SceneInfo;
-import envoy.data.User.UserStatus;
-import envoy.event.UserStatusChange;
-import envoy.util.EnvoyLog;
-
-import dev.kske.eventbus.EventBus;
+import envoy.client.ui.controller.ChatScene;
 
 /**
  * Contains methods that change something about the currently logged in user.
@@ -23,11 +27,13 @@ import dev.kske.eventbus.EventBus;
  */
 public final class UserUtil {
 
+	private static final Context	context	= Context.getInstance();
+	private static final Logger		logger	= EnvoyLog.getLogger(UserUtil.class);
+
 	private UserUtil() {}
 
 	/**
-	 * Logs the current user out and reopens
-	 * {@link envoy.client.ui.controller.LoginScene}.
+	 * Logs the current user out and reopens {@link envoy.client.ui.controller.LoginScene}.
 	 *
 	 * @since Envoy Client v0.2-beta
 	 */
@@ -40,13 +46,13 @@ public final class UserUtil {
 			EnvoyLog.getLogger(ShutdownHelper.class).log(Level.INFO, "A logout was requested");
 			EventBus.getInstance().dispatch(new EnvoyCloseEvent());
 			EventBus.getInstance().dispatch(new Logout());
-			Context.getInstance().getSceneContext().load(SceneInfo.LOGIN_SCENE);
+			context.getSceneContext().load(SceneInfo.LOGIN_SCENE);
+			logger.log(Level.INFO, "A logout occurred.");
 		});
 	}
 
 	/**
-	 * Notifies the application that the status of the currently logged in user has
-	 * changed.
+	 * Notifies the application that the status of the currently logged in user has changed.
 	 *
 	 * @param newStatus the new status
 	 * @since Envoy Client v0.3-beta
@@ -54,11 +60,65 @@ public final class UserUtil {
 	public static void changeStatus(UserStatus newStatus) {
 
 		// Sending the already active status is a valid action
-		if (newStatus.equals(Context.getInstance().getLocalDB().getUser().getStatus())) return;
+		if (newStatus.equals(context.getLocalDB().getUser().getStatus()))
+			return;
 		else {
 			EventBus.getInstance().dispatch(new OwnStatusChange(newStatus));
-			if (Context.getInstance().getClient().isOnline())
-				Context.getInstance().getClient().send(new UserStatusChange(Context.getInstance().getLocalDB().getUser().getID(), newStatus));
+			if (context.getClient().isOnline())
+				context.getClient()
+					.send(new UserStatusChange(context.getLocalDB().getUser().getID(), newStatus));
+			logger.log(Level.INFO, "A manual status change occurred.");
+		}
+	}
+
+	/**
+	 * Removes the given contact.
+	 *
+	 * @param block the contact that should be removed
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void disableContact(Contact block) {
+		if (!context.getClient().isOnline() || block == null)
+			return;
+		else {
+			final var alert = new Alert(AlertType.CONFIRMATION);
+			alert.setContentText("Are you sure you want to "
+				+ (block instanceof User ? "block " : "leave group ") + block.getName() + "?");
+			AlertHelper.confirmAction(alert, () -> {
+				final var isUser = block instanceof User;
+				context.getClient()
+					.send(isUser ? new UserOperation((User) block, ElementOperation.REMOVE)
+						: new GroupResize(context.getLocalDB().getUser(), (Group) block,
+							ElementOperation.REMOVE));
+				if (!isUser)
+					block.getContacts().remove(context.getLocalDB().getUser());
+				EventBus.getInstance().dispatch(new ContactDisabled(block));
+				logger.log(Level.INFO, isUser ? "A user was blocked." : "The user left a group.");
+			});
+		}
+	}
+
+	/**
+	 * Deletes the given contact with all his messages entirely.
+	 *
+	 * @param delete the contact to delete
+	 * @since Envoy Client v0.3-beta
+	 */
+	public static void deleteContact(Contact delete) {
+		if (delete == null)
+			return;
+		else {
+			final var alert = new Alert(AlertType.CONFIRMATION);
+			alert.setContentText("Are you sure you want to delete " + delete.getName()
+				+ " entirely? All messages with this contact will be deleted. This action cannot be undone.");
+			AlertHelper.confirmAction(alert, () -> {
+				context.getLocalDB().getUsers().remove(delete.getName());
+				context.getLocalDB().getChats()
+					.removeIf(chat -> chat.getRecipient().equals(delete));
+				if (context.getSceneContext().getController() instanceof ChatScene)
+					((ChatScene) context.getSceneContext().getController()).resetState();
+				logger.log(Level.INFO, "A contact with all his messages was deleted.");
+			});
 		}
 	}
 }
diff --git a/client/src/main/java/module-info.java b/client/src/main/java/module-info.java
index d894c26..8f9f8e0 100644
--- a/client/src/main/java/module-info.java
+++ b/client/src/main/java/module-info.java
@@ -1,6 +1,5 @@
 /**
- * This module contains all classes defining the client application of the Envoy
- * project.
+ * This module contains all classes defining the client application of the Envoy project.
  *
  * @author Kai S. K. Engelbart
  * @author Leon Hofmeister
diff --git a/client/src/main/resources/client.properties b/client/src/main/resources/client.properties
index 2e97815..35ddb28 100644
--- a/client/src/main/resources/client.properties
+++ b/client/src/main/resources/client.properties
@@ -1,6 +1,5 @@
+fileLevelBarrier=OFF
+consoleLevelBarrier=FINER
 server=localhost
 port=8080
-localDB=localDB
 localDBSaveInterval=2
-consoleLevelBarrier=FINER
-fileLevelBarrier=OFF
diff --git a/client/src/main/resources/css/base.css b/client/src/main/resources/css/base.css
index 28d276c..4c46161 100644
--- a/client/src/main/resources/css/base.css
+++ b/client/src/main/resources/css/base.css
@@ -139,20 +139,25 @@
 
 .tab-pane {
     -fx-tab-max-height: 0.0 ;
-} 
+}
+
 .tab-pane .tab-header-area {
     visibility: hidden ;
     -fx-padding: -20.0 0.0 0.0 0.0;
 }
 
+.disabled-chat {
+	-fx-background-color: #0000FF;
+}
+
 #quick-select-list .scroll-bar:horizontal{
-	-fx-pref-height: 0;
-	-fx-max-height: 0;
-	-fx-min-height: 0; 
+	-fx-pref-height: 0.0;
+	-fx-max-height: 0.0;
+	-fx-min-height: 0.0; 
 }
 
 #quick-select-list .scroll-bar:vertical{
-	-fx-pref-width: 0;
-	-fx-max-width: 0;
-	-fx-min-width: 0; 
+	-fx-pref-width: 0.0;
+	-fx-max-width: 0.0;
+	-fx-min-width: 0.0; 
 }
diff --git a/client/src/main/resources/fxml/ChatScene.fxml b/client/src/main/resources/fxml/ChatScene.fxml
index d3fb6e9..d61325c 100644
--- a/client/src/main/resources/fxml/ChatScene.fxml
+++ b/client/src/main/resources/fxml/ChatScene.fxml
@@ -126,15 +126,6 @@
 										<ListView id="chat-list" fx:id="chatList"
 											focusTraversable="false" onMouseClicked="#chatListClicked"
 											prefWidth="316.0" VBox.vgrow="ALWAYS">
-											<contextMenu>
-												<ContextMenu anchorLocation="CONTENT_TOP_LEFT">
-													<items>
-														<MenuItem fx:id="deleteContactMenuItem"
-															mnemonicParsing="false" onAction="#deleteContact"
-															text="Delete" />
-													</items>
-												</ContextMenu>
-											</contextMenu>
 											<padding>
 												<Insets bottom="5.0" left="5.0" right="2.0" top="5.0" />
 											</padding>
@@ -167,7 +158,7 @@
 				<HBox id="transparent-background" fx:id="ownContactControl">
 					<children>
 						<Region id="transparent-background" prefWidth="120"
-							fx:id="spaceBetweenUserAndSettingsButton" />
+							fx:id="spaceBetweenUserAndSettingsButton" HBox.hgrow="ALWAYS" />
 						<Button fx:id="settingsButton" mnemonicParsing="false"
 							onAction="#settingsButtonClicked" prefHeight="30.0"
 							prefWidth="30.0" text="" alignment="CENTER">
diff --git a/common/src/main/java/envoy/data/Attachment.java b/common/src/main/java/envoy/data/Attachment.java
index 31e83fb..0be0e1f 100644
--- a/common/src/main/java/envoy/data/Attachment.java
+++ b/common/src/main/java/envoy/data/Attachment.java
@@ -3,8 +3,8 @@ package envoy.data;
 import java.io.Serializable;
 
 /**
- * This interface should be used for any type supposed to be a {@link Message}
- * attachment (i.e. images or sound).
+ * This interface should be used for any type supposed to be a {@link Message} attachment (i.e.
+ * images or sound).
  *
  * @author Leon Hofmeister
  * @author Kai S. K. Engelbart
diff --git a/common/src/main/java/envoy/data/Config.java b/common/src/main/java/envoy/data/Config.java
index 74798fb..34c02fd 100644
--- a/common/src/main/java/envoy/data/Config.java
+++ b/common/src/main/java/envoy/data/Config.java
@@ -9,15 +9,13 @@ import java.util.stream.Collectors;
 import envoy.util.EnvoyLog;
 
 /**
- * Manages all application settings that are set during application startup by
- * either loading them from the {@link Properties} file (default values)
- * {@code client.properties} or parsing them from the command line arguments of
- * the application.
+ * Manages all application settings that are set during application startup by either loading them
+ * from the {@link Properties} file (default values) {@code client.properties} or parsing them from
+ * the command line arguments of the application.
  * <p>
- * All items inside the {@code Config} are supposed to either be supplied over
- * default value or over command line argument. Developers that fail to provide
- * default values will be greeted with an error message the next time they try
- * to start Envoy...
+ * All items inside the {@code Config} are supposed to either be supplied over default value or over
+ * command line argument. Developers that fail to provide default values will be greeted with an
+ * error message the next time they try to start Envoy...
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Common v0.1-beta
@@ -44,15 +42,14 @@ public class Config {
 	 */
 	private void load(Properties properties) {
 		items.entrySet().stream().filter(e -> properties.containsKey(e.getKey()))
-				.forEach(e -> e.getValue().parse(properties.getProperty(e.getKey())));
+			.forEach(e -> e.getValue().parse(properties.getProperty(e.getKey())));
 	}
 
 	/**
 	 * Parses config items from an array of command line arguments.
 	 *
 	 * @param args the command line arguments to parse
-	 * @throws IllegalStateException if a malformed command line argument has been
-	 *                               supplied
+	 * @throws IllegalStateException if a malformed command line argument has been supplied
 	 * @since Envoy Common v0.1-beta
 	 */
 	private void load(String[] args) {
@@ -61,7 +58,7 @@ public class Config {
 				if (args[i].startsWith("--")) {
 					if (args[i].length() == 2)
 						throw new IllegalStateException(
-								"Malformed command line argument at position " + i + ": " + args[i]);
+							"Malformed command line argument at position " + i + ": " + args[i]);
 					final String commandLong = args[i].substring(2);
 					if (item.getCommandLong().equals(commandLong)) {
 						item.parse(args[++i]);
@@ -70,7 +67,7 @@ public class Config {
 				} else if (args[i].startsWith("-")) {
 					if (args[i].length() == 1)
 						throw new IllegalStateException(
-								"Malformed command line argument at position " + i + ": " + args[i]);
+							"Malformed command line argument at position " + i + ": " + args[i]);
 					final String commandShort = args[i].substring(1);
 					if (item.getCommandShort().equals(commandShort)) {
 						item.parse(args[++i]);
@@ -78,35 +75,36 @@ public class Config {
 					}
 				} else
 					throw new IllegalStateException(
-							"Malformed command line argument at position " + i + ": " + args[i]);
+						"Malformed command line argument at position " + i + ": " + args[i]);
 	}
 
 	/**
-	 * Supplies default values from the given .properties file and parses the
-	 * configuration from an array of command line arguments.
+	 * Supplies default values from the given .properties file and parses the configuration from an
+	 * array of command line arguments.
 	 *
 	 * @param declaringClass     the class calling this method
-	 * @param propertiesFilePath the path to where the .properties file can be found
-	 *                           - will be only the file name if it is located
-	 *                           directly inside the {@code src/main/resources}
-	 *                           folder
+	 * @param propertiesFilePath the path to where the .properties file can be found - will be only
+	 *                           the file name if it is located directly inside the
+	 *                           {@code src/main/resources} folder
 	 * @param args               the command line arguments to parse
-	 * @throws IllegalStateException if this method is getting called again or if a
-	 *                               malformed command line argument has been
-	 *                               supplied
+	 * @throws IllegalStateException if this method is getting called again or if a malformed
+	 *                               command line argument has been supplied
 	 * @since Envoy Common v0.1-beta
 	 */
 	public void loadAll(Class<?> declaringClass, String propertiesFilePath, String[] args) {
 		if (modificationDisabled)
-			throw new IllegalStateException("Cannot change config after isInitialized has been called");
+			throw new IllegalStateException(
+				"Cannot change config after isInitialized has been called");
 
 		// Load the defaults from the given .properties file first
 		final var properties = new Properties();
 		try {
-			properties.load(declaringClass.getClassLoader().getResourceAsStream(propertiesFilePath));
+			properties
+				.load(declaringClass.getClassLoader().getResourceAsStream(propertiesFilePath));
 		} catch (final IOException e) {
-			EnvoyLog.getLogger(Config.class).log(Level.SEVERE, "An error occurred when reading in the configuration: ",
-					e);
+			EnvoyLog.getLogger(Config.class).log(Level.SEVERE,
+				"An error occurred when reading in the configuration: ",
+				e);
 		}
 		load(properties);
 
@@ -122,13 +120,13 @@ public class Config {
 	}
 
 	/**
-	 * @throws IllegalStateException if a {@link ConfigItem} has not been
-	 *                               initialized
+	 * @throws IllegalStateException if a {@link ConfigItem} has not been initialized
 	 * @since Envoy Common v0.1-beta
 	 */
 	private void isInitialized() {
-		String uninitialized = items.values().stream().filter(c -> c.get() == null).map(ConfigItem::getCommandLong).collect(Collectors.joining(", "));
-		if(!uninitialized.isEmpty())
+		String uninitialized = items.values().stream().filter(c -> c.get() == null)
+			.map(ConfigItem::getCommandLong).collect(Collectors.joining(", "));
+		if (!uninitialized.isEmpty())
 			throw new IllegalStateException("Config items uninitialized: " + uninitialized);
 	}
 
@@ -148,11 +146,11 @@ public class Config {
 	 * @param <T>           the type of the {@link ConfigItem}
 	 * @param commandName   the key for this config item as well as its long name
 	 * @param commandShort  the abbreviation of this config item
-	 * @param parseFunction the {@code Function<String, T>} that parses the value
-	 *                      from a string
+	 * @param parseFunction the {@code Function<String, T>} that parses the value from a string
 	 * @since Envoy Common v0.2-beta
 	 */
-	protected <T> void put(String commandName, String commandShort, Function<String, T> parseFunction) {
+	protected <T> void put(String commandName, String commandShort,
+		Function<String, T> parseFunction) {
 		items.put(commandName, new ConfigItem<>(commandName, commandShort, parseFunction));
 	}
 
@@ -160,17 +158,13 @@ public class Config {
 	 * @return the directory in which all local files are saves
 	 * @since Envoy Client v0.2-beta
 	 */
-	public File getHomeDirectory() {
-		return (File) items.get("homeDirectory").get();
-	}
+	public File getHomeDirectory() { return (File) items.get("homeDirectory").get(); }
 
 	/**
 	 * @return the minimal {@link Level} to log inside the log file
 	 * @since Envoy Client v0.2-beta
 	 */
-	public Level getFileLevelBarrier() {
-		return (Level) items.get("fileLevelBarrier").get();
-	}
+	public Level getFileLevelBarrier() { return (Level) items.get("fileLevelBarrier").get(); }
 
 	/**
 	 * @return the minimal {@link Level} to log inside the console
diff --git a/common/src/main/java/envoy/data/ConfigItem.java b/common/src/main/java/envoy/data/ConfigItem.java
index e3bdc42..0ef6df9 100644
--- a/common/src/main/java/envoy/data/ConfigItem.java
+++ b/common/src/main/java/envoy/data/ConfigItem.java
@@ -3,8 +3,8 @@ package envoy.data;
 import java.util.function.Function;
 
 /**
- * Contains a single {@link Config} value as well as the corresponding command
- * line arguments and its default value.
+ * Contains a single {@link Config} value as well as the corresponding command line arguments and
+ * its default value.
  * <p>
  * All {@code ConfigItem}s are automatically mandatory.
  *
@@ -24,8 +24,7 @@ public final class ConfigItem<T> {
 	 *
 	 * @param commandLong   the long command line argument to set this value
 	 * @param commandShort  the short command line argument to set this value
-	 * @param parseFunction the {@code Function<String, T>} that parses the value
-	 *                      from a string
+	 * @param parseFunction the {@code Function<String, T>} that parses the value from a string
 	 * @since Envoy Common v0.1-beta
 	 */
 	public ConfigItem(String commandLong, String commandShort, Function<String, T> parseFunction) {
@@ -40,18 +39,18 @@ public final class ConfigItem<T> {
 	 * @param input the string to parse from
 	 * @since Envoy Common v0.1-beta
 	 */
-	public void parse(String input) { value = parseFunction.apply(input); }
+	public void parse(String input) {
+		value = parseFunction.apply(input);
+	}
 
 	/**
-	 * @return The long command line argument to set the value of this
-	 *         {@link ConfigItem}
+	 * @return The long command line argument to set the value of this {@link ConfigItem}
 	 * @since Envoy Common v0.1-beta
 	 */
 	public String getCommandLong() { return commandLong; }
 
 	/**
-	 * @return The short command line argument to set the value of this
-	 *         {@link ConfigItem}
+	 * @return The short command line argument to set the value of this {@link ConfigItem}
 	 * @since Envoy Common v0.1-beta
 	 */
 	public String getCommandShort() { return commandShort; }
@@ -60,7 +59,9 @@ public final class ConfigItem<T> {
 	 * @return the value of this {@link ConfigItem}
 	 * @since Envoy Common v0.1-beta
 	 */
-	public T get() { return value; }
+	public T get() {
+		return value;
+	}
 
 	/**
 	 * @param value the value to set
diff --git a/common/src/main/java/envoy/data/Contact.java b/common/src/main/java/envoy/data/Contact.java
index 278b056..8e250dc 100644
--- a/common/src/main/java/envoy/data/Contact.java
+++ b/common/src/main/java/envoy/data/Contact.java
@@ -53,23 +53,27 @@ public abstract class Contact implements Serializable {
 
 	/**
 	 * Provides a hash code based on the ID of this contact.
-	 * 
+	 *
 	 * @since Envoy Common v0.1-beta
 	 */
 	@Override
-	public final int hashCode() { return Objects.hash(id); }
+	public final int hashCode() {
+		return Objects.hash(id);
+	}
 
 	/**
-	 * Tests equality to another object. If that object is a contact as well,
-	 * equality is determined by the ID.
-	 * 
+	 * Tests equality to another object. If that object is a contact as well, equality is determined
+	 * by the ID.
+	 *
 	 * @param obj the object to test for equality to this contact
 	 * @return {code true} if both objects are contacts and have identical IDs
 	 */
 	@Override
 	public final boolean equals(Object obj) {
-		if (this == obj) return true;
-		if (!(obj instanceof Contact)) return false;
+		if (this == obj)
+			return true;
+		if (!(obj instanceof Contact))
+			return false;
 		return id == ((Contact) obj).id;
 	}
 
diff --git a/common/src/main/java/envoy/data/Group.java b/common/src/main/java/envoy/data/Group.java
index 40a0cb1..257b603 100644
--- a/common/src/main/java/envoy/data/Group.java
+++ b/common/src/main/java/envoy/data/Group.java
@@ -18,7 +18,9 @@ public final class Group extends Contact {
 	 * @param name the name of this group
 	 * @since Envoy Common v0.1-beta
 	 */
-	public Group(long id, String name) { this(id, name, new HashSet<User>()); }
+	public Group(long id, String name) {
+		this(id, name, new HashSet<User>());
+	}
 
 	/**
 	 * Creates an instance of a {@link Group}.
@@ -28,10 +30,14 @@ public final class Group extends Contact {
 	 * @param members all members that should be preinitialized
 	 * @since Envoy Common v0.1-beta
 	 */
-	public Group(long id, String name, Set<User> members) { super(id, name, members); }
+	public Group(long id, String name, Set<User> members) {
+		super(id, name, members);
+	}
 
 	@Override
-	public String toString() { return String.format("Group[id=%d,name=%s,%d member(s)]", id, name, contacts.size()); }
+	public String toString() {
+		return String.format("Group[id=%d,name=%s,%d member(s)]", id, name, contacts.size());
+	}
 
 	private void readObject(ObjectInputStream inputStream) throws Exception {
 		inputStream.defaultReadObject();
diff --git a/common/src/main/java/envoy/data/GroupMessage.java b/common/src/main/java/envoy/data/GroupMessage.java
index fec27f8..d6a30a9 100644
--- a/common/src/main/java/envoy/data/GroupMessage.java
+++ b/common/src/main/java/envoy/data/GroupMessage.java
@@ -14,11 +14,9 @@ public final class GroupMessage extends Message {
 	private static final long serialVersionUID = 1L;
 
 	/**
-	 * Initializes a {@link GroupMessage} with values for all of its properties. The
-	 * use
-	 * of this constructor is only intended for the {@link MessageBuilder} class, as
-	 * this class provides {@code null} checks and default values for all
-	 * properties.
+	 * Initializes a {@link GroupMessage} with values for all of its properties. The use of this
+	 * constructor is only intended for the {@link MessageBuilder} class, as this class provides
+	 * {@code null} checks and default values for all properties.
 	 *
 	 * @param id             unique ID
 	 * @param senderID       the ID of the user who sends the message
@@ -28,16 +26,18 @@ public final class GroupMessage extends Message {
 	 * @param readDate       the read date of the message
 	 * @param text           the text content of the message
 	 * @param attachment     the attachment of the message, if present
-	 * @param status         the current {@link Message.MessageStatus} of the
-	 *                       message
+	 * @param status         the current {@link Message.MessageStatus} of the message
 	 * @param forwarded      whether this message was forwarded
 	 * @param memberStatuses a map of all members and their status according to this
 	 *                       {@link GroupMessage}
 	 * @since Envoy Common v0.2-beta
 	 */
-	GroupMessage(long id, long senderID, long groupID, Instant creationDate, Instant receivedDate, Instant readDate, String text,
-			Attachment attachment, MessageStatus status, boolean forwarded, Map<Long, MessageStatus> memberStatuses) {
-		super(id, senderID, groupID, creationDate, receivedDate, readDate, text, attachment, status, forwarded);
+	GroupMessage(long id, long senderID, long groupID, Instant creationDate, Instant receivedDate,
+		Instant readDate, String text,
+		Attachment attachment, MessageStatus status, boolean forwarded,
+		Map<Long, MessageStatus> memberStatuses) {
+		super(id, senderID, groupID, creationDate, receivedDate, readDate, text, attachment, status,
+			forwarded);
 		this.memberStatuses = memberStatuses;
 	}
 
diff --git a/common/src/main/java/envoy/data/IDGenerator.java b/common/src/main/java/envoy/data/IDGenerator.java
index 774c348..a080b03 100644
--- a/common/src/main/java/envoy/data/IDGenerator.java
+++ b/common/src/main/java/envoy/data/IDGenerator.java
@@ -30,20 +30,25 @@ public final class IDGenerator implements IEvent, Serializable {
 	}
 
 	@Override
-	public String toString() { return String.format("IDGenerator[current=%d,end=%d]", current, end); }
+	public String toString() {
+		return String.format("IDGenerator[current=%d,end=%d]", current, end);
+	}
 
 	/**
 	 * @return {@code true} if there are unused IDs remaining
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public boolean hasNext() { return current < end; }
+	public boolean hasNext() {
+		return current < end;
+	}
 
 	/**
 	 * @return the next ID
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public long next() {
-		if (!hasNext()) throw new IllegalStateException("All IDs have been used");
+		if (!hasNext())
+			throw new IllegalStateException("All IDs have been used");
 		return current++;
 	}
 }
diff --git a/common/src/main/java/envoy/data/LoginCredentials.java b/common/src/main/java/envoy/data/LoginCredentials.java
index 3848989..292c2e2 100644
--- a/common/src/main/java/envoy/data/LoginCredentials.java
+++ b/common/src/main/java/envoy/data/LoginCredentials.java
@@ -4,11 +4,9 @@ import java.io.Serializable;
 import java.time.Instant;
 
 /**
- * Contains a {@link User}'s login / registration information as well as the
- * client version.
+ * Contains a {@link User}'s login / registration information as well as the client version.
  * <p>
- * If the authentication is performed with a token, the token is stored instead
- * of the password.
+ * If the authentication is performed with a token, the token is stored instead of the password.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Common v0.2-alpha
@@ -21,8 +19,9 @@ public final class LoginCredentials implements Serializable {
 
 	private static final long serialVersionUID = 4;
 
-	private LoginCredentials(String identifier, String password, boolean registration, boolean token, boolean requestToken, String clientVersion,
-			Instant lastSync) {
+	private LoginCredentials(String identifier, String password, boolean registration,
+		boolean token, boolean requestToken, String clientVersion,
+		Instant lastSync) {
 		this.identifier		= identifier;
 		this.password		= password;
 		this.registration	= registration;
@@ -43,8 +42,10 @@ public final class LoginCredentials implements Serializable {
 	 * @return the created login credentials
 	 * @since Envoy Common v0.2-beta
 	 */
-	public static LoginCredentials login(String identifier, String password, boolean requestToken, String clientVersion, Instant lastSync) {
-		return new LoginCredentials(identifier, password, false, false, requestToken, clientVersion, lastSync);
+	public static LoginCredentials login(String identifier, String password, boolean requestToken,
+		String clientVersion, Instant lastSync) {
+		return new LoginCredentials(identifier, password, false, false, requestToken, clientVersion,
+			lastSync);
 	}
 
 	/**
@@ -57,7 +58,8 @@ public final class LoginCredentials implements Serializable {
 	 * @return the created login credentials
 	 * @since Envoy Common v0.2-beta
 	 */
-	public static LoginCredentials loginWithToken(String identifier, String token, String clientVersion, Instant lastSync) {
+	public static LoginCredentials loginWithToken(String identifier, String token,
+		String clientVersion, Instant lastSync) {
 		return new LoginCredentials(identifier, token, false, true, false, clientVersion, lastSync);
 	}
 
@@ -72,19 +74,22 @@ public final class LoginCredentials implements Serializable {
 	 * @return the created login credentials
 	 * @since Envoy Common v0.2-beta
 	 */
-	public static LoginCredentials registration(String identifier, String password, boolean requestToken, String clientVersion, Instant lastSync) {
-		return new LoginCredentials(identifier, password, true, false, requestToken, clientVersion, lastSync);
+	public static LoginCredentials registration(String identifier, String password,
+		boolean requestToken, String clientVersion, Instant lastSync) {
+		return new LoginCredentials(identifier, password, true, false, requestToken, clientVersion,
+			lastSync);
 	}
 
 	@Override
 	public String toString() {
-		return String.format("LoginCredentials[identifier=%s,registration=%b,token=%b,requestToken=%b,clientVersion=%s,lastSync=%s]",
-				identifier,
-				registration,
-				token,
-				requestToken,
-				clientVersion,
-				lastSync);
+		return String.format(
+			"LoginCredentials[identifier=%s,registration=%b,token=%b,requestToken=%b,clientVersion=%s,lastSync=%s]",
+			identifier,
+			registration,
+			token,
+			requestToken,
+			clientVersion,
+			lastSync);
 	}
 
 	/**
@@ -100,24 +105,27 @@ public final class LoginCredentials implements Serializable {
 	public String getPassword() { return password; }
 
 	/**
-	 * @return {@code true} if these credentials are used for user registration
-	 *         instead of user login
+	 * @return {@code true} if these credentials are used for user registration instead of user
+	 *         login
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public boolean isRegistration() { return registration; }
 
 	/**
-	 * @return {@code true} if these credentials use an authentication token instead
-	 *         of a password
+	 * @return {@code true} if these credentials use an authentication token instead of a password
 	 * @since Envoy Common v0.2-beta
 	 */
-	public boolean usesToken() { return token; }
+	public boolean usesToken() {
+		return token;
+	}
 
 	/**
 	 * @return {@code true} if the server should generate a new authentication token
 	 * @since Envoy Common v0.2-beta
 	 */
-	public boolean requestToken() { return requestToken; }
+	public boolean requestToken() {
+		return requestToken;
+	}
 
 	/**
 	 * @return the version of the client sending these credentials
diff --git a/common/src/main/java/envoy/data/Message.java b/common/src/main/java/envoy/data/Message.java
index e642566..b8965a3 100644
--- a/common/src/main/java/envoy/data/Message.java
+++ b/common/src/main/java/envoy/data/Message.java
@@ -6,9 +6,8 @@ import java.time.Instant;
 import dev.kske.eventbus.IEvent;
 
 /**
- * Represents a unique message with a unique, numeric ID. Further metadata
- * includes the sender and recipient {@link User}s, as well as the creation
- * date and the current {@link MessageStatus}.<br>
+ * Represents a unique message with a unique, numeric ID. Further metadata includes the sender and
+ * recipient {@link User}s, as well as the creation date and the current {@link MessageStatus}.<br>
  *
  * @author Kai S. K. Engelbart
  * @author Leon Hofmeister
@@ -56,10 +55,9 @@ public class Message implements Serializable, IEvent {
 	private static final long serialVersionUID = 2L;
 
 	/**
-	 * Initializes a {@link Message} with values for all of its properties. The use
-	 * of this constructor is only intended for the {@link MessageBuilder} class, as
-	 * this class provides {@code null} checks and default values for all
-	 * properties.
+	 * Initializes a {@link Message} with values for all of its properties. The use of this
+	 * constructor is only intended for the {@link MessageBuilder} class, as this class provides
+	 * {@code null} checks and default values for all properties.
 	 *
 	 * @param id           unique ID
 	 * @param senderID     the ID of the user who sends the message
@@ -73,8 +71,9 @@ public class Message implements Serializable, IEvent {
 	 * @param forwarded    whether this message was forwarded
 	 * @since Envoy Common v0.2-beta
 	 */
-	Message(long id, long senderID, long recipientID, Instant creationDate, Instant receivedDate, Instant readDate, String text,
-			Attachment attachment, MessageStatus status, boolean forwarded) {
+	Message(long id, long senderID, long recipientID, Instant creationDate, Instant receivedDate,
+		Instant readDate, String text,
+		Attachment attachment, MessageStatus status, boolean forwarded) {
 		this.id				= id;
 		this.senderID		= senderID;
 		this.recipientID	= recipientID;
@@ -101,21 +100,23 @@ public class Message implements Serializable, IEvent {
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public void nextStatus() {
-		if (status == MessageStatus.READ) throw new IllegalStateException("Message status READ is already reached");
+		if (status == MessageStatus.READ)
+			throw new IllegalStateException("Message status READ is already reached");
 		status = MessageStatus.values()[status.ordinal() + 1];
 	}
 
 	@Override
 	public String toString() {
-		return String.format("Message[id=%d,sender=%s,recipient=%s,date=%s,status=%s,text=%s,forwarded=%b,hasAttachment=%b]",
-				id,
-				senderID,
-				recipientID,
-				creationDate,
-				status,
-				text,
-				forwarded,
-				attachment != null);
+		return String.format(
+			"Message[id=%d,sender=%s,recipient=%s,date=%s,status=%s,text=%s,forwarded=%b,hasAttachment=%b]",
+			id,
+			senderID,
+			recipientID,
+			creationDate,
+			status,
+			text,
+			forwarded,
+			attachment != null);
 	}
 
 	/**
@@ -149,8 +150,7 @@ public class Message implements Serializable, IEvent {
 	public Instant getReceivedDate() { return receivedDate; }
 
 	/**
-	 * @param receivedDate the date at which the message has been received by the
-	 *                     sender
+	 * @param receivedDate the date at which the message has been received by the sender
 	 * @since Envoy Common v0.2-beta
 	 */
 	public void setReceivedDate(Instant receivedDate) { this.receivedDate = receivedDate; }
@@ -183,7 +183,9 @@ public class Message implements Serializable, IEvent {
 	 * @return {@code true} if an attachment is present
 	 * @since Envoy Common v0.1-beta
 	 */
-	public boolean hasAttachment() { return attachment != null; }
+	public boolean hasAttachment() {
+		return attachment != null;
+	}
 
 	/**
 	 * @return the current status of this message
@@ -196,7 +198,8 @@ public class Message implements Serializable, IEvent {
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public void setStatus(MessageStatus status) {
-		if (status.ordinal() < this.status.ordinal()) throw new IllegalStateException("This message is moving backwards in time");
+		if (status.ordinal() < this.status.ordinal())
+			throw new IllegalStateException("This message is moving backwards in time");
 		this.status = status;
 	}
 
diff --git a/common/src/main/java/envoy/data/MessageBuilder.java b/common/src/main/java/envoy/data/MessageBuilder.java
index 9c5eb95..6c60de2 100644
--- a/common/src/main/java/envoy/data/MessageBuilder.java
+++ b/common/src/main/java/envoy/data/MessageBuilder.java
@@ -25,20 +25,21 @@ public final class MessageBuilder {
 	private boolean					forwarded;
 
 	/**
-	 * Creates an instance of {@link MessageBuilder} with all mandatory values
-	 * without defaults for the {@link Message} class.
+	 * Creates an instance of {@link MessageBuilder} with all mandatory values without defaults for
+	 * the {@link Message} class.
 	 *
 	 * @param senderID    the ID of the user who sends the {@link Message}
 	 * @param recipientID the ID of the user who receives the {@link Message}
-	 * @param idGenerator the ID generator used to generate a unique {@link Message}
-	 *                    id
+	 * @param idGenerator the ID generator used to generate a unique {@link Message} id
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public MessageBuilder(long senderID, long recipientID, IDGenerator idGenerator) { this(senderID, recipientID, idGenerator.next()); }
+	public MessageBuilder(long senderID, long recipientID, IDGenerator idGenerator) {
+		this(senderID, recipientID, idGenerator.next());
+	}
 
 	/**
-	 * Creates an instance of {@link MessageBuilder} with all mandatory values
-	 * without defaults for the {@link Message} class.
+	 * Creates an instance of {@link MessageBuilder} with all mandatory values without defaults for
+	 * the {@link Message} class.
 	 *
 	 * @param senderID    the ID of the user who sends the {@link Message}
 	 * @param recipientID the ID of the user who receives the {@link Message}
@@ -52,14 +53,12 @@ public final class MessageBuilder {
 	}
 
 	/**
-	 * This constructor transforms a given {@link Message} into a new message for a
-	 * new receiver.
+	 * This constructor transforms a given {@link Message} into a new message for a new receiver.
 	 * This makes it especially useful in the case of forwarding messages.
 	 *
 	 * @param msg         the message to copy
 	 * @param recipientID the ID of the user who receives the {@link Message}
-	 * @param iDGenerator the ID generator used to generate a unique {@link Message}
-	 *                    id
+	 * @param iDGenerator the ID generator used to generate a unique {@link Message} id
 	 * @since Envoy v0.1-beta
 	 */
 	public MessageBuilder(Message msg, long recipientID, IDGenerator iDGenerator) {
@@ -72,79 +71,69 @@ public final class MessageBuilder {
 	}
 
 	/**
-	 * Creates an instance of {@link Message} with the previously supplied values.
-	 * If a mandatory value is not set, a default value will be used instead:<br>
+	 * Creates an instance of {@link Message} with the previously supplied values. If a mandatory
+	 * value is not set, a default value will be used instead:<br>
 	 * <br>
-	 * {@code date}
-	 * {@code Instant.now()} and {@code null} for {@code receivedDate} and
-	 * {@code readDate}
-	 * <br>
-	 * {@code text}
-	 * {@code ""}
-	 * <br>
-	 * {@code status}
-	 * {@code MessageStatus.WAITING}
+	 * {@code date} {@code Instant.now()} and {@code null} for {@code receivedDate} and
+	 * {@code readDate} <br>
+	 * {@code text} {@code ""} <br>
+	 * {@code status} {@code MessageStatus.WAITING}
 	 *
 	 * @return a new instance of {@link Message}
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public Message build() {
 		supplyDefaults();
-		return new Message(id, senderID, recipientID, creationDate, receivedDate, readDate, text, attachment, status, forwarded);
+		return new Message(id, senderID, recipientID, creationDate, receivedDate, readDate, text,
+			attachment, status, forwarded);
 	}
 
 	/**
-	 * Creates an instance of {@link GroupMessage} with the previously supplied
-	 * values. <br>
+	 * Creates an instance of {@link GroupMessage} with the previously supplied values. <br>
 	 * <b> Sets all member statuses to {@link MessageStatus#WAITING}.</b><br>
-	 * If a mandatory value is not set, a default value will be used
-	 * instead:<br>
-	 * <br>
-	 * {@code time stamp}
-	 * {@code Instant.now()}
-	 * <br>
-	 * {@code text}
-	 * {@code ""}
+	 * If a mandatory value is not set, a default value will be used instead:<br>
 	 * <br>
+	 * {@code time stamp} {@code Instant.now()} <br>
+	 * {@code text} {@code ""} <br>
 	 *
-	 * @param group the {@link Group} that is used to fill the map of member
-	 *              statuses
+	 * @param group the {@link Group} that is used to fill the map of member statuses
 	 * @return a new instance of {@link GroupMessage}
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public GroupMessage buildGroupMessage(Group group) {
 		final var memberStatuses = new HashMap<Long, Message.MessageStatus>();
-		group.getContacts().forEach(user -> memberStatuses.put(user.getID(), MessageStatus.WAITING));
+		group.getContacts()
+			.forEach(user -> memberStatuses.put(user.getID(), MessageStatus.WAITING));
 		return buildGroupMessage(group, memberStatuses);
 	}
 
 	/**
-	 * Creates an instance of {@link GroupMessage} with the previously supplied
-	 * values. If a mandatory value is not set, a default value will be used
-	 * instead:<br>
+	 * Creates an instance of {@link GroupMessage} with the previously supplied values. If a
+	 * mandatory value is not set, a default value will be used instead:<br>
 	 * <br>
-	 * {@code time stamp}
-	 * {@code Instant.now()}
-	 * <br>
-	 * {@code text}
-	 * {@code ""}
+	 * {@code time stamp} {@code Instant.now()} <br>
+	 * {@code text} {@code ""}
 	 *
-	 * @param group          the {@link Group} that is used to fill the map of
-	 *                       member statuses
+	 * @param group          the {@link Group} that is used to fill the map of member statuses
 	 * @param memberStatuses the map of all current statuses
 	 * @return a new instance of {@link GroupMessage}
 	 * @since Envoy Common v0.1-beta
 	 */
 	public GroupMessage buildGroupMessage(Group group, Map<Long, MessageStatus> memberStatuses) {
-		if (group == null || memberStatuses == null) throw new NullPointerException();
+		if (group == null || memberStatuses == null)
+			throw new NullPointerException();
 		supplyDefaults();
-		return new GroupMessage(id, senderID, recipientID, creationDate, receivedDate, readDate, text, attachment, status, forwarded, memberStatuses);
+		return new GroupMessage(id, senderID, recipientID, creationDate, receivedDate, readDate,
+			text, attachment, status, forwarded, memberStatuses);
 	}
 
 	private void supplyDefaults() {
-		if (creationDate == null) creationDate = Instant.now();
-		if (text == null) text = "";
-		if (status == null) status = MessageStatus.WAITING;
+		if (creationDate == null)
+			creationDate = Instant.now();
+		if (text == null)
+			text = "";
+		if (status == null)
+			status = MessageStatus.WAITING;
 	}
 
 	/**
@@ -188,8 +177,7 @@ public final class MessageBuilder {
 	}
 
 	/**
-	 * @param attachment the {@link Attachment} of the {@link Message} to
-	 *                   create
+	 * @param attachment the {@link Attachment} of the {@link Message} to create
 	 * @return this {@link MessageBuilder}
 	 * @since Envoy Common v0.2-alpha
 	 */
diff --git a/common/src/main/java/envoy/data/User.java b/common/src/main/java/envoy/data/User.java
index ab83070..f0f2a62 100644
--- a/common/src/main/java/envoy/data/User.java
+++ b/common/src/main/java/envoy/data/User.java
@@ -4,8 +4,7 @@ import java.io.*;
 import java.util.*;
 
 /**
- * Represents a unique user with a unique, numeric ID, a name and a current
- * {@link UserStatus}.<br>
+ * Represents a unique user with a unique, numeric ID, a name and a current {@link UserStatus}.<br>
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Common v0.2-alpha
@@ -34,8 +33,7 @@ public final class User extends Contact {
 		ONLINE,
 
 		/**
-		 * select this, if a user is online but unavailable at the moment (sudden
-		 * interruption)
+		 * select this, if a user is online but unavailable at the moment (sudden interruption)
 		 */
 		AWAY,
 
@@ -52,8 +50,7 @@ public final class User extends Contact {
 
 	/**
 	 * Initializes a {@link User}. <br>
-	 * The {@link UserStatus} is set to {@link UserStatus#ONLINE}.
-	 * No contacts are initialized.
+	 * The {@link UserStatus} is set to {@link UserStatus#ONLINE}. No contacts are initialized.
 	 *
 	 * @param id   unique ID
 	 * @param name user name
@@ -94,7 +91,8 @@ public final class User extends Contact {
 
 	@Override
 	public String toString() {
-		return String.format("User[id=%d,name=%s,status=%s", id, name, status) + (contacts.isEmpty() ? "]" : "," + contacts.size() + " contact(s)]");
+		return String.format("User[id=%d,name=%s,status=%s", id, name, status)
+			+ (contacts.isEmpty() ? "]" : "," + contacts.size() + " contact(s)]");
 	}
 
 	/**
@@ -119,15 +117,18 @@ public final class User extends Contact {
 	private void writeObject(ObjectOutputStream outputStream) throws Exception {
 		outputStream.defaultWriteObject();
 		if (serializeContacts) {
-			getContacts().stream().filter(User.class::isInstance).map(User.class::cast).forEach(user -> user.serializeContacts = false);
+			getContacts().stream().filter(User.class::isInstance).map(User.class::cast)
+				.forEach(user -> user.serializeContacts = false);
 			outputStream.writeObject(getContacts());
-		} else outputStream.writeObject(new HashSet<>());
+		} else
+			outputStream.writeObject(new HashSet<>());
 	}
 
 	/**
-	 * @param serializeContacts whether the contacts of this {@link User} should be
-	 *                          serialized
+	 * @param serializeContacts whether the contacts of this {@link User} should be serialized
 	 * @since Envoy Common v0.1-beta
 	 */
-	public void serializeContacts(boolean serializeContacts) { this.serializeContacts = serializeContacts; }
+	public void serializeContacts(boolean serializeContacts) {
+		this.serializeContacts = serializeContacts;
+	}
 }
diff --git a/common/src/main/java/envoy/data/package-info.java b/common/src/main/java/envoy/data/package-info.java
index 10865d0..a89330f 100644
--- a/common/src/main/java/envoy/data/package-info.java
+++ b/common/src/main/java/envoy/data/package-info.java
@@ -1,6 +1,5 @@
 /**
- * This package contains all data objects that are used both by Envoy Client and
- * by Envoy Server.
+ * This package contains all data objects that are used both by Envoy Client and by Envoy Server.
  *
  * @author Leon Hofmeister
  * @author Maximilian K&auml;fer
diff --git a/common/src/main/java/envoy/event/ElementOperation.java b/common/src/main/java/envoy/event/ElementOperation.java
index e585a84..8977511 100644
--- a/common/src/main/java/envoy/event/ElementOperation.java
+++ b/common/src/main/java/envoy/event/ElementOperation.java
@@ -3,8 +3,7 @@ package envoy.event;
 /**
  * This enum declares all modification possibilities for a given container.
  * <p>
- * These can be: {@link ElementOperation#ADD} or
- * {@link ElementOperation#REMOVE}.
+ * These can be: {@link ElementOperation#ADD} or {@link ElementOperation#REMOVE}.
  *
  * @author Leon Hofmeister
  * @since Envoy Common v0.1-beta
@@ -12,14 +11,12 @@ package envoy.event;
 public enum ElementOperation {
 
 	/**
-	 * Select this element, if the given element should be added to the given
-	 * container.
+	 * Select this element, if the given element should be added to the given container.
 	 */
 	ADD,
 
 	/**
-	 * Select this element, if the given element should be removed from the given
-	 * container.
+	 * Select this element, if the given element should be removed from the given container.
 	 */
 	REMOVE
 }
diff --git a/common/src/main/java/envoy/event/Event.java b/common/src/main/java/envoy/event/Event.java
index da3bc72..e12b882 100644
--- a/common/src/main/java/envoy/event/Event.java
+++ b/common/src/main/java/envoy/event/Event.java
@@ -5,9 +5,9 @@ import java.io.Serializable;
 import dev.kske.eventbus.IEvent;
 
 /**
- * This class serves as a convenience base class for all events. It implements
- * the {@link IEvent} interface and provides a generic value. For events without
- * a value there also is {@link envoy.event.Event.Valueless}.
+ * This class serves as a convenience base class for all events. It implements the {@link IEvent}
+ * interface and provides a generic value. For events without a value there also is
+ * {@link envoy.event.Event.Valueless}.
  *
  * @author Kai S. K. Engelbart
  * @param <T> the type of the Event
@@ -19,15 +19,21 @@ public abstract class Event<T> implements IEvent, Serializable {
 
 	private static final long serialVersionUID = 0L;
 
-	protected Event(T value) { this.value = value; }
+	protected Event(T value) {
+		this.value = value;
+	}
 
 	/**
 	 * @return the data associated with this event
 	 */
-	public T get() { return value; }
+	public T get() {
+		return value;
+	}
 
 	@Override
-	public String toString() { return String.format("%s[value=%s]", this.getClass().getSimpleName(), value); }
+	public String toString() {
+		return String.format("%s[value=%s]", this.getClass().getSimpleName(), value);
+	}
 
 	/**
 	 * Serves as a super class for events that do not carry a value.
@@ -39,9 +45,13 @@ public abstract class Event<T> implements IEvent, Serializable {
 
 		private static final long serialVersionUID = 0L;
 
-		protected Valueless() { super(null); }
+		protected Valueless() {
+			super(null);
+		}
 
 		@Override
-		public String toString() { return this.getClass().getSimpleName(); }
+		public String toString() {
+			return this.getClass().getSimpleName();
+		}
 	}
 }
diff --git a/common/src/main/java/envoy/event/GroupCreation.java b/common/src/main/java/envoy/event/GroupCreation.java
index 02270ee..f4de822 100644
--- a/common/src/main/java/envoy/event/GroupCreation.java
+++ b/common/src/main/java/envoy/event/GroupCreation.java
@@ -17,20 +17,19 @@ public final class GroupCreation extends Event<String> {
 	private static final long serialVersionUID = 0L;
 
 	/**
-	 * @param value            the name of this group at creation time
-	 * @param initialMemberIDs the IDs of all {@link User}s that should be group
-	 *                         members from the beginning on (excluding the creator
-	 *                         of this group)
+	 * @param name             the name of this group at creation time
+	 * @param initialMemberIDs the IDs of all {@link User}s that should be group members from the
+	 *                         beginning on (excluding the creator of this group)
 	 * @since Envoy Common v0.1-beta
 	 */
-	public GroupCreation(String value, Set<Long> initialMemberIDs) {
-		super(value);
+	public GroupCreation(String name, Set<Long> initialMemberIDs) {
+		super(name);
 		this.initialMemberIDs = initialMemberIDs != null ? initialMemberIDs : new HashSet<>();
 	}
 
 	/**
-	 * @return the IDs of all {@link User}s that are members from the beginning
-	 *         (excluding the creator of this group)
+	 * @return the IDs of all {@link User}s that are members from the beginning (excluding the
+	 *         creator of this group)
 	 * @since Envoy Common v0.1-beta
 	 */
 	public Set<Long> getInitialMemberIDs() { return initialMemberIDs; }
diff --git a/common/src/main/java/envoy/event/GroupCreationResult.java b/common/src/main/java/envoy/event/GroupCreationResult.java
index 3944ec2..c1a002b 100644
--- a/common/src/main/java/envoy/event/GroupCreationResult.java
+++ b/common/src/main/java/envoy/event/GroupCreationResult.java
@@ -1,21 +1,35 @@
 package envoy.event;
 
+import envoy.data.Group;
+
 /**
- * Used to communicate with a client that his request to create a group might
- * have been rejected as it might be disabled on his current server.
+ * Used to communicate with a client that his request to create a group might have been rejected as
+ * it might be disabled on his current server.
  *
  * @author Leon Hofmeister
  * @since Envoy Common v0.2-beta
  */
-public class GroupCreationResult extends Event<Boolean> {
+public class GroupCreationResult extends Event<Group> {
 
 	private static final long serialVersionUID = 1L;
 
 	/**
-	 * Creates a new {@code GroupCreationResult}.
+	 * Creates a new {@code GroupCreationResult} that implies the failure of this
+	 * {@link GroupCreationResult}.
 	 *
-	 * @param success whether the GroupCreation sent before was successful
 	 * @since Envoy Common v0.2-beta
 	 */
-	public GroupCreationResult(boolean success) { super(success); }
+	public GroupCreationResult() {
+		super(null);
+	}
+
+	/**
+	 * Creates a new {@code GroupCreationResult}.
+	 *
+	 * @param resultGroup the group the server created
+	 * @since Envoy Common v0.2-beta
+	 */
+	public GroupCreationResult(Group resultGroup) {
+		super(resultGroup);
+	}
 }
diff --git a/common/src/main/java/envoy/event/GroupMessageStatusChange.java b/common/src/main/java/envoy/event/GroupMessageStatusChange.java
index 30d286e..bd5f326 100644
--- a/common/src/main/java/envoy/event/GroupMessageStatusChange.java
+++ b/common/src/main/java/envoy/event/GroupMessageStatusChange.java
@@ -17,11 +17,10 @@ public final class GroupMessageStatusChange extends MessageStatusChange {
 
 	/**
 	 * Initializes a {@link GroupMessageStatusChange}.
-	 * 
+	 *
 	 * @param id       the ID of the {@link GroupMessage} this event is related to
 	 * @param status   the status of this specific members {@link GroupMessage}
-	 * @param date     the date at which the MessageStatus change occurred for
-	 *                 this specific member
+	 * @param date     the date at which the MessageStatus change occurred for this specific member
 	 * @param memberID the ID of the group member that caused the status change
 	 * @since Envoy Common v0.2-beta
 	 */
@@ -37,5 +36,8 @@ public final class GroupMessageStatusChange extends MessageStatusChange {
 	public long getMemberID() { return memberID; }
 
 	@Override
-	public String toString() { return String.format("GroupMessageStatusChange[meta=%s,memberID=%d]", super.toString(), memberID); }
+	public String toString() {
+		return String.format("GroupMessageStatusChange[meta=%s,memberID=%d]", super.toString(),
+			memberID);
+	}
 }
diff --git a/common/src/main/java/envoy/event/GroupResize.java b/common/src/main/java/envoy/event/GroupResize.java
index c8e8c76..69e0447 100644
--- a/common/src/main/java/envoy/event/GroupResize.java
+++ b/common/src/main/java/envoy/event/GroupResize.java
@@ -5,11 +5,9 @@ import static envoy.event.ElementOperation.*;
 import envoy.data.*;
 
 /**
- * This event is used to communicate changes in the group size between client
- * and server.
+ * This event is used to communicate changes in the group size between client and server.
  * <p>
- * Possible actions are adding or removing certain {@link User}s to or from a
- * certain {@link Group}.
+ * Possible actions are adding or removing certain {@link User}s to or from a certain {@link Group}.
  *
  * @author Leon Hofmeister
  * @since Envoy Common v0.1-beta
@@ -22,8 +20,7 @@ public final class GroupResize extends Event<User> {
 	private static final long serialVersionUID = 0L;
 
 	/**
-	 * Initializes a {@link GroupResize} through a Contact where the name has
-	 * already been set.
+	 * Initializes a {@link GroupResize} through a Contact where the name has already been set.
 	 *
 	 * @param user      the {@link User} who wants to join or leave a group
 	 * @param group     the {@link Group} he wants to join or leave
@@ -33,13 +30,14 @@ public final class GroupResize extends Event<User> {
 	 */
 	public GroupResize(User user, Group group, ElementOperation operation) {
 		super(user);
-		this.operation	= operation;
-		if (group.getContacts().contains(user)) {
-			if (operation.equals(ADD))
-				throw new IllegalArgumentException(String.format("Cannot add %s to %s!", user, group));
-		} else if (operation.equals(REMOVE))
-			throw new IllegalArgumentException(String.format("Cannot remove %s from %s!", user, group));
-		groupID	= group.getID();
+		this.operation = operation;
+		final var contained = group.getContacts().contains(user);
+		if (contained && operation.equals(ADD))
+			throw new IllegalArgumentException(String.format("Cannot add %s to %s!", user, group));
+		else if (operation.equals(REMOVE) && !contained)
+			throw new IllegalArgumentException(
+				String.format("Cannot remove %s from %s!", user, group));
+		groupID = group.getID();
 	}
 
 	/**
@@ -72,5 +70,8 @@ public final class GroupResize extends Event<User> {
 	}
 
 	@Override
-	public String toString() { return String.format("GroupResize[userid=%d,groupid=%d,operation=%s]", get(), groupID, operation); }
+	public String toString() {
+		return String.format("GroupResize[user=%s,groupid=%d,operation=%s]", get(), groupID,
+			operation);
+	}
 }
diff --git a/common/src/main/java/envoy/event/HandshakeRejection.java b/common/src/main/java/envoy/event/HandshakeRejection.java
index 6895fff..0ac79fe 100644
--- a/common/src/main/java/envoy/event/HandshakeRejection.java
+++ b/common/src/main/java/envoy/event/HandshakeRejection.java
@@ -1,8 +1,7 @@
 package envoy.event;
 
 /**
- * Signifies to the client that the handshake failed for the attached
- * reason.
+ * Signifies to the client that the handshake failed for the attached reason.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Common v0.3-alpha
@@ -24,8 +23,7 @@ public final class HandshakeRejection extends Event<String> {
 	public static final String USERNAME_TAKEN = "Incorrect user name or password.";
 
 	/**
-	 * Select this value if the version of the client is incompatible with the
-	 * server.
+	 * Select this value if the version of the client is incompatible with the server.
 	 *
 	 * @since Envoy Common v0.1-beta
 	 */
@@ -39,8 +37,7 @@ public final class HandshakeRejection extends Event<String> {
 	public static final String INVALID_TOKEN = "Invalid authentication token";
 
 	/**
-	 * Select this value if the handshake could not be completed for some different
-	 * reason.
+	 * Select this value if the handshake could not be completed for some different reason.
 	 *
 	 * @since Envoy Common v0.3-alpha
 	 */
@@ -54,7 +51,9 @@ public final class HandshakeRejection extends Event<String> {
 	 *
 	 * @since Envoy Common v0.3-alpha
 	 */
-	public HandshakeRejection() { super(INTERNAL_ERROR); }
+	public HandshakeRejection() {
+		super(INTERNAL_ERROR);
+	}
 
 	/**
 	 * Creates an instance of {@link HandshakeRejection}.
@@ -62,5 +61,7 @@ public final class HandshakeRejection extends Event<String> {
 	 * @param reason the reason why the handshake was rejected
 	 * @since Envoy Common v0.3-alpha
 	 */
-	public HandshakeRejection(String reason) { super(reason); }
+	public HandshakeRejection(String reason) {
+		super(reason);
+	}
 }
diff --git a/common/src/main/java/envoy/event/IDGeneratorRequest.java b/common/src/main/java/envoy/event/IDGeneratorRequest.java
index 09e8265..0c9881a 100644
--- a/common/src/main/java/envoy/event/IDGeneratorRequest.java
+++ b/common/src/main/java/envoy/event/IDGeneratorRequest.java
@@ -1,8 +1,7 @@
 package envoy.event;
 
 /**
- * Signifies to the server that the client needs a new
- * {@link envoy.data.IDGenerator} instance.
+ * Signifies to the server that the client needs a new {@link envoy.data.IDGenerator} instance.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Common v0.3-alpha
diff --git a/common/src/main/java/envoy/event/IsTyping.java b/common/src/main/java/envoy/event/IsTyping.java
index 0b6f544..4c5e93e 100644
--- a/common/src/main/java/envoy/event/IsTyping.java
+++ b/common/src/main/java/envoy/event/IsTyping.java
@@ -1,8 +1,7 @@
 package envoy.event;
 
 /**
- * This event should be sent when a user is currently typing something in a
- * chat.
+ * This event should be sent when a user is currently typing something in a chat.
  *
  * @author Leon Hofmeister
  * @since Envoy Client v0.2-beta
diff --git a/common/src/main/java/envoy/event/IssueProposal.java b/common/src/main/java/envoy/event/IssueProposal.java
index b12b6fd..d015e88 100644
--- a/common/src/main/java/envoy/event/IssueProposal.java
+++ b/common/src/main/java/envoy/event/IssueProposal.java
@@ -1,8 +1,8 @@
 package envoy.event;
 
 /**
- * This class allows envoy users to send an issue proposal to the server who, if
- * not disabled by its administrator, will forward it directly to Gitea.
+ * This class allows envoy users to send an issue proposal to the server who, if not disabled by its
+ * administrator, will forward it directly to Gitea.
  *
  * @author Leon Hofmeister
  * @since Envoy Common v0.2-beta
@@ -17,9 +17,8 @@ public final class IssueProposal extends Event<String> {
 	/**
 	 * @param title       the title of the reported bug
 	 * @param description the description of this bug
-	 * @param isBug       determines whether this {@code IssueProposal} is
-	 *                    supposed to be a
-	 *                    feature or a bug (true = bug, false = feature)
+	 * @param isBug       determines whether this {@code IssueProposal} is supposed to be a feature
+	 *                    or a bug (true = bug, false = feature)
 	 * @since Envoy Common v0.2-beta
 	 */
 	public IssueProposal(String title, String description, boolean isBug) {
@@ -32,14 +31,14 @@ public final class IssueProposal extends Event<String> {
 	 * @param title       the title of the reported bug
 	 * @param description the description of this bug
 	 * @param user        the name of the user creating the issue
-	 * @param isBug       determines whether this {@code IssueProposal} is
-	 *                    supposed to be a
-	 *                    feature or a bug (true = bug, false = feature)
+	 * @param isBug       determines whether this {@code IssueProposal} is supposed to be a feature
+	 *                    or a bug (true = bug, false = feature)
 	 * @since Envoy Common v0.2-beta
 	 */
 	public IssueProposal(String title, String description, String user, boolean isBug) {
 		super(escape(title));
-		this.description	= sanitizeDescription(description) + String.format("<br>Submitted by user %s.", user);
+		this.description	=
+			sanitizeDescription(description) + String.format("<br>Submitted by user %s.", user);
 		bug					= isBug;
 	}
 
@@ -61,7 +60,9 @@ public final class IssueProposal extends Event<String> {
 	 * @return the escaped string
 	 * @since Envoy Client v0.2-beta
 	 */
-	private static String escape(String raw) { return raw.replace("\\", "\\\\").replace("\"", "\\\""); }
+	private static String escape(String raw) {
+		return raw.replace("\\", "\\\\").replace("\"", "\\\"");
+	}
 
 	/**
 	 * @return the description
@@ -70,8 +71,7 @@ public final class IssueProposal extends Event<String> {
 	public String getDescription() { return description; }
 
 	/**
-	 * @return whether this issue is supposed to be a bug - otherwise it is intended
-	 *         as a feature
+	 * @return whether this issue is supposed to be a bug - otherwise it is intended as a feature
 	 * @since Envoy Common v0.2-beta
 	 */
 	public boolean isBug() { return bug; }
diff --git a/common/src/main/java/envoy/event/MessageStatusChange.java b/common/src/main/java/envoy/event/MessageStatusChange.java
index 33e2cb3..5bdacde 100644
--- a/common/src/main/java/envoy/event/MessageStatusChange.java
+++ b/common/src/main/java/envoy/event/MessageStatusChange.java
@@ -19,8 +19,7 @@ public class MessageStatusChange extends Event<Message.MessageStatus> {
 	 * Initializes a {@link MessageStatusChange}.
 	 *
 	 * @param id     the ID of the {@link Message} this event is related to
-	 * @param status the status of the {@link Message} this event is related
-	 *               to
+	 * @param status the status of the {@link Message} this event is related to
 	 * @param date   the date at which the MessageStatus change occurred
 	 * @since Envoy Common v0.2-beta
 	 */
@@ -36,7 +35,9 @@ public class MessageStatusChange extends Event<Message.MessageStatus> {
 	 * @param message the message from which to build the event
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public MessageStatusChange(Message message) { this(message.getID(), message.getStatus(), Instant.now()); }
+	public MessageStatusChange(Message message) {
+		this(message.getID(), message.getStatus(), Instant.now());
+	}
 
 	/**
 	 * @return the ID of the {@link Message} this event is related to
@@ -51,5 +52,7 @@ public class MessageStatusChange extends Event<Message.MessageStatus> {
 	public Instant getDate() { return date; }
 
 	@Override
-	public String toString() { return String.format("MessageStatusChange[id=%d,status=%s,date=%s]", id, value, date); }
+	public String toString() {
+		return String.format("MessageStatusChange[id=%d,status=%s,date=%s]", id, value, date);
+	}
 }
diff --git a/common/src/main/java/envoy/event/NameChange.java b/common/src/main/java/envoy/event/NameChange.java
index 368f4bc..a62bf5d 100644
--- a/common/src/main/java/envoy/event/NameChange.java
+++ b/common/src/main/java/envoy/event/NameChange.java
@@ -5,8 +5,7 @@ import envoy.data.Contact;
 /**
  * This event informs
  * <p>
- * a) the server of the name change of a user or a group.
- * b) another user of this users name change.
+ * a) the server of the name change of a user or a group. b) another user of this users name change.
  *
  * @author Leon Hofmeister
  * @since Envoy Common v0.1-beta
@@ -15,7 +14,7 @@ public final class NameChange extends Event<String> {
 
 	private final long id;
 
-	private static final long	serialVersionUID	= 0L;
+	private static final long serialVersionUID = 0L;
 
 	/**
 	 * Creates a new {@link NameChange} for a user or a group.
@@ -30,13 +29,14 @@ public final class NameChange extends Event<String> {
 	}
 
 	/**
-	 * Initializes a {@link NameChange} through a Contact where the name has
-	 * already been set.
+	 * Initializes a {@link NameChange} through a Contact where the name has already been set.
 	 *
 	 * @param contact the contact whose name was updated
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public NameChange(Contact contact) { this(contact.getID(), contact.getName()); }
+	public NameChange(Contact contact) {
+		this(contact.getID(), contact.getName());
+	}
 
 	/**
 	 * @return the ID of the {@link Contact} this event is related to
@@ -45,5 +45,7 @@ public final class NameChange extends Event<String> {
 	public long getID() { return id; }
 
 	@Override
-	public String toString() { return String.format("NameChange[id=%d,name=%s]", id, value); }
+	public String toString() {
+		return String.format("NameChange[id=%d,name=%s]", id, value);
+	}
 }
diff --git a/common/src/main/java/envoy/event/NewAuthToken.java b/common/src/main/java/envoy/event/NewAuthToken.java
index 82dccca..c232189 100644
--- a/common/src/main/java/envoy/event/NewAuthToken.java
+++ b/common/src/main/java/envoy/event/NewAuthToken.java
@@ -21,5 +21,7 @@ public class NewAuthToken extends Event<String> {
 	}
 
 	@Override
-	public String toString() { return "NewAuthToken"; }
+	public String toString() {
+		return "NewAuthToken";
+	}
 }
diff --git a/common/src/main/java/envoy/event/NoAttachments.java b/common/src/main/java/envoy/event/NoAttachments.java
index 3622569..02ee7f0 100644
--- a/common/src/main/java/envoy/event/NoAttachments.java
+++ b/common/src/main/java/envoy/event/NoAttachments.java
@@ -1,8 +1,7 @@
 package envoy.event;
 
 /**
- * This event is used so that the server can tell the client that attachments
- * will be filtered out.
+ * This event is used so that the server can tell the client that attachments will be filtered out.
  *
  * @author Leon Hofmeister
  * @since Envoy Common v0.2-beta
diff --git a/common/src/main/java/envoy/event/PasswordChangeRequest.java b/common/src/main/java/envoy/event/PasswordChangeRequest.java
index 59ec8fb..b1b860c 100644
--- a/common/src/main/java/envoy/event/PasswordChangeRequest.java
+++ b/common/src/main/java/envoy/event/PasswordChangeRequest.java
@@ -38,5 +38,7 @@ public final class PasswordChangeRequest extends Event<String> {
 	public String getOldPassword() { return oldPassword; }
 
 	@Override
-	public String toString() { return "PasswordChangeRequest[id=" + id + "]"; }
+	public String toString() {
+		return "PasswordChangeRequest[id=" + id + "]";
+	}
 }
diff --git a/common/src/main/java/envoy/event/PasswordChangeResult.java b/common/src/main/java/envoy/event/PasswordChangeResult.java
index 716404c..320c7a2 100644
--- a/common/src/main/java/envoy/event/PasswordChangeResult.java
+++ b/common/src/main/java/envoy/event/PasswordChangeResult.java
@@ -1,8 +1,8 @@
 package envoy.event;
 
 /**
- * This class acts as a notice to the user whether his
- * {@link envoy.event.PasswordChangeRequest} was successful.
+ * This class acts as a notice to the user whether his {@link envoy.event.PasswordChangeRequest} was
+ * successful.
  *
  * @author Leon Hofmeister
  * @since Envoy Common v0.2-beta
@@ -14,9 +14,10 @@ public final class PasswordChangeResult extends Event<Boolean> {
 	/**
 	 * Creates an instance of {@code PasswordChangeResult}.
 	 *
-	 * @param value whether the preceding {@link envoy.event.PasswordChangeRequest}
-	 *              was successful.
+	 * @param value whether the preceding {@link envoy.event.PasswordChangeRequest} was successful.
 	 * @since Envoy Common v0.2-beta
 	 */
-	public PasswordChangeResult(boolean value) { super(value); }
+	public PasswordChangeResult(boolean value) {
+		super(value);
+	}
 }
diff --git a/common/src/main/java/envoy/event/UserStatusChange.java b/common/src/main/java/envoy/event/UserStatusChange.java
index 5a26f50..33afe56 100644
--- a/common/src/main/java/envoy/event/UserStatusChange.java
+++ b/common/src/main/java/envoy/event/UserStatusChange.java
@@ -17,8 +17,7 @@ public final class UserStatusChange extends Event<UserStatus> {
 	 * Initializes a {@link UserStatusChange}.
 	 *
 	 * @param id     the ID of the {@link User} this event is related to
-	 * @param status the status of the {@link User} this event is related
-	 *               to
+	 * @param status the status of the {@link User} this event is related to
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public UserStatusChange(long id, User.UserStatus status) {
@@ -32,7 +31,9 @@ public final class UserStatusChange extends Event<UserStatus> {
 	 * @param user the User from which to build the event
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public UserStatusChange(User user) { this(user.getID(), user.getStatus()); }
+	public UserStatusChange(User user) {
+		this(user.getID(), user.getStatus());
+	}
 
 	/**
 	 * @return the ID of the {@link User} this event is related to
@@ -41,5 +42,7 @@ public final class UserStatusChange extends Event<UserStatus> {
 	public long getID() { return id; }
 
 	@Override
-	public String toString() { return String.format("UserStatusChange[id=%d,status=%s]", id, value); }
+	public String toString() {
+		return String.format("UserStatusChange[id=%d,status=%s]", id, value);
+	}
 }
diff --git a/common/src/main/java/envoy/event/contact/ContactsChangedSinceLastLogin.java b/common/src/main/java/envoy/event/contact/ContactsChangedSinceLastLogin.java
new file mode 100644
index 0000000..2626001
--- /dev/null
+++ b/common/src/main/java/envoy/event/contact/ContactsChangedSinceLastLogin.java
@@ -0,0 +1,15 @@
+package envoy.event.contact;
+
+import envoy.event.Event.Valueless;
+
+/**
+ * Conveys that either a direct contact or a group member has been deleted while the user has been
+ * offline.
+ *
+ * @author Leon Hofmeister
+ * @since Envoy Common v0.3-beta
+ */
+public class ContactsChangedSinceLastLogin extends Valueless {
+
+	private static final long serialVersionUID = 1L;
+}
diff --git a/common/src/main/java/envoy/event/contact/ContactOperation.java b/common/src/main/java/envoy/event/contact/UserOperation.java
similarity index 55%
rename from common/src/main/java/envoy/event/contact/ContactOperation.java
rename to common/src/main/java/envoy/event/contact/UserOperation.java
index a31d147..bbec1c9 100644
--- a/common/src/main/java/envoy/event/contact/ContactOperation.java
+++ b/common/src/main/java/envoy/event/contact/UserOperation.java
@@ -1,35 +1,41 @@
 package envoy.event.contact;
 
-import envoy.data.Contact;
+import envoy.data.User;
 import envoy.event.*;
 
 /**
  * Signifies the modification of a contact list.
  *
  * @author Maximilian K&auml;fer
- * @since Envoy Common v0.2-alpha
+ * @since Envoy Common v0.3-beta
  */
-public final class ContactOperation extends Event<Contact> {
+public final class UserOperation extends Event<User> {
 
 	private final ElementOperation operationType;
 
 	private static final long serialVersionUID = 1L;
 
 	/**
-	 * Initializes a {@link ContactOperation}.
+	 * Initializes a {@link UserOperation}.
 	 *
 	 * @param contact       the user on which the operation is performed
 	 * @param operationType the type of operation to perform
-	 * @since Envoy Common v0.2-alpha
+	 * @since Envoy Common v0.3-beta
 	 */
-	public ContactOperation(Contact contact, ElementOperation operationType) {
+	public UserOperation(User contact, ElementOperation operationType) {
 		super(contact);
 		this.operationType = operationType;
 	}
 
 	/**
 	 * @return the type of operation to perform
-	 * @since Envoy Common v0.2-alpha
+	 * @since Envoy Common v0.3-beta
 	 */
 	public ElementOperation getOperationType() { return operationType; }
+
+	@Override
+	public String toString() {
+		return String.format("%s[contact=%s, operation=%s]", UserOperation.class.getSimpleName(),
+			value, operationType);
+	}
 }
diff --git a/common/src/main/java/envoy/event/contact/UserSearchRequest.java b/common/src/main/java/envoy/event/contact/UserSearchRequest.java
index 6eb1925..71ca351 100644
--- a/common/src/main/java/envoy/event/contact/UserSearchRequest.java
+++ b/common/src/main/java/envoy/event/contact/UserSearchRequest.java
@@ -18,5 +18,7 @@ public final class UserSearchRequest extends Event<String> {
 	 * @param searchPhrase the search phrase to use in the user search
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public UserSearchRequest(String searchPhrase) { super(searchPhrase); }
+	public UserSearchRequest(String searchPhrase) {
+		super(searchPhrase);
+	}
 }
diff --git a/common/src/main/java/envoy/event/contact/UserSearchResult.java b/common/src/main/java/envoy/event/contact/UserSearchResult.java
index 6b1358b..cb39bb5 100644
--- a/common/src/main/java/envoy/event/contact/UserSearchResult.java
+++ b/common/src/main/java/envoy/event/contact/UserSearchResult.java
@@ -21,5 +21,7 @@ public final class UserSearchResult extends Event<List<User>> {
 	 * @param users the users found during the search
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public UserSearchResult(List<User> users) { super(users); }
+	public UserSearchResult(List<User> users) {
+		super(users);
+	}
 }
diff --git a/common/src/main/java/envoy/event/package-info.java b/common/src/main/java/envoy/event/package-info.java
index 81e8563..5ed80da 100644
--- a/common/src/main/java/envoy/event/package-info.java
+++ b/common/src/main/java/envoy/event/package-info.java
@@ -1,6 +1,6 @@
 /**
- * This package contains all events that can be sent or received by Envoy Client
- * or Envoy Server Standalone.
+ * This package contains all events that can be sent or received by Envoy Client or Envoy Server
+ * Standalone.
  *
  * @author Leon Hofmeister
  * @author Maximilian K&auml;fer
diff --git a/common/src/main/java/envoy/exception/EnvoyException.java b/common/src/main/java/envoy/exception/EnvoyException.java
index a09b460..da0482c 100644
--- a/common/src/main/java/envoy/exception/EnvoyException.java
+++ b/common/src/main/java/envoy/exception/EnvoyException.java
@@ -12,20 +12,24 @@ public final class EnvoyException extends Exception {
 	 * @param message the message to display once this Exception is thrown
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public EnvoyException(String message) { super(message); }
+	public EnvoyException(String message) {
+		super(message);
+	}
 
 	/**
 	 * @param message the message to display once this Exception is thrown
-	 * @param cause   the {@link Throwable} which resulted in the throw of an
-	 *                EnvoyException
+	 * @param cause   the {@link Throwable} which resulted in the throw of an EnvoyException
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public EnvoyException(String message, Throwable cause) { super(message, cause); }
+	public EnvoyException(String message, Throwable cause) {
+		super(message, cause);
+	}
 
 	/**
-	 * @param cause the {@link Throwable} which resulted in the throw of an
-	 *              EnvoyException
+	 * @param cause the {@link Throwable} which resulted in the throw of an EnvoyException
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public EnvoyException(Throwable cause) { super(cause); }
+	public EnvoyException(Throwable cause) {
+		super(cause);
+	}
 }
diff --git a/common/src/main/java/envoy/util/Bounds.java b/common/src/main/java/envoy/util/Bounds.java
index 8f8f381..20868f3 100644
--- a/common/src/main/java/envoy/util/Bounds.java
+++ b/common/src/main/java/envoy/util/Bounds.java
@@ -26,13 +26,16 @@ public final class Bounds {
 	 * @return {@code true} if the given contact name is valid
 	 * @since Envoy Common v0.1-beta
 	 */
-	public static boolean isValidContactName(String contactName) { return CONTACT_NAME_PATTERN.matcher(contactName).matches(); }
+	public static boolean isValidContactName(String contactName) {
+		return CONTACT_NAME_PATTERN.matcher(contactName).matches();
+	}
 
 	/**
 	 * @return the maximum size allowed for a user/ group name.
-	 * @apiNote has to be updated manually if {@link Bounds#CONTACT_NAME_PATTERN}
-	 *          gets updated.
+	 * @apiNote has to be updated manually if {@link Bounds#CONTACT_NAME_PATTERN} gets updated.
 	 * @since Envoy Common v0.1-beta
 	 */
-	public static int maximumUsernameSize() { return 16; }
+	public static int maximumUsernameSize() {
+		return 16;
+	}
 }
diff --git a/common/src/main/java/envoy/util/EnvoyLog.java b/common/src/main/java/envoy/util/EnvoyLog.java
index 55f3a42..83563d8 100644
--- a/common/src/main/java/envoy/util/EnvoyLog.java
+++ b/common/src/main/java/envoy/util/EnvoyLog.java
@@ -8,8 +8,7 @@ import java.util.logging.*;
 import envoy.data.Config;
 
 /**
- * Configures the {@link java.util.logging} API to output the log into the
- * console and a log file.
+ * Configures the {@link java.util.logging} API to output the log into the console and a log file.
  *
  * @author Leon Hofmeister
  * @author Kai S. K. Engelbart
@@ -30,20 +29,23 @@ public final class EnvoyLog {
 	 * @since Envoy Common v0.1-beta
 	 */
 	public static void initialize(Config config) {
-		if (initialized) throw new IllegalStateException("EnvoyLog is already initialized");
+		if (initialized)
+			throw new IllegalStateException("EnvoyLog is already initialized");
 
 		// Remove default console handler
 		LogManager.getLogManager().reset();
 
 		// Configure log file
 		final File logFile = new File(config.getHomeDirectory(),
-				"log/" + DateTimeFormatter.ofPattern("yyyy-MM-dd--hh-mm").format(LocalDateTime.now()) + ".log");
+			"log/" + DateTimeFormatter.ofPattern("yyyy-MM-dd--hh-mm").format(LocalDateTime.now())
+				+ ".log");
 		logFile.getParentFile().mkdirs();
 
 		// Configure formatting
 		// Sample log entry: [2020-06-13 16:50:26] [INFORMATION]
 		// [envoy.client.ui.Startup] Closing connection...
-		System.setProperty("java.util.logging.SimpleFormatter.format", "[%1$tF %1$tT] [%4$-7s] [%3$s] %5$s %6$s%n");
+		System.setProperty("java.util.logging.SimpleFormatter.format",
+			"[%1$tF %1$tT] [%4$-7s] [%3$s] %5$s %6$s%n");
 		final SimpleFormatter formatter = new SimpleFormatter();
 
 		try {
@@ -69,20 +71,22 @@ public final class EnvoyLog {
 	}
 
 	/**
-	 * Configures all loggers that are contained within the hierarchy of a specific
-	 * path to use the console and file handlers.
+	 * Configures all loggers that are contained within the hierarchy of a specific path to use the
+	 * console and file handlers.
 	 *
 	 * @param path the path to the loggers to configure
 	 * @since Envoy Common v0.1-beta
 	 */
 	private static void attach(String path) {
-		if (!initialized) throw new IllegalStateException("EnvoyLog is not initialized");
+		if (!initialized)
+			throw new IllegalStateException("EnvoyLog is not initialized");
 
 		// Get root logger
 		final Logger logger = Logger.getLogger(path);
 
 		// Add handlers
-		if (fileHandler != null) logger.addHandler(fileHandler);
+		if (fileHandler != null)
+			logger.addHandler(fileHandler);
 		logger.addHandler(consoleHandler);
 
 		// Delegate logger level filtering to the handlers
@@ -90,12 +94,14 @@ public final class EnvoyLog {
 	}
 
 	/**
-	 * Creates a logger for a specified class, which output will be displayed inside
-	 * the console and written to the log file.
+	 * Creates a logger for a specified class, which output will be displayed inside the console and
+	 * written to the log file.
 	 *
 	 * @param logClass the class in which the logger is used
 	 * @return the created logger
 	 * @since Envoy Common v0.1-beta
 	 */
-	public static Logger getLogger(Class<?> logClass) { return Logger.getLogger(logClass.getCanonicalName()); }
+	public static Logger getLogger(Class<?> logClass) {
+		return Logger.getLogger(logClass.getCanonicalName());
+	}
 }
diff --git a/common/src/main/java/envoy/util/SerializationUtils.java b/common/src/main/java/envoy/util/SerializationUtils.java
index f556657..80b91ac 100644
--- a/common/src/main/java/envoy/util/SerializationUtils.java
+++ b/common/src/main/java/envoy/util/SerializationUtils.java
@@ -19,7 +19,9 @@ public final class SerializationUtils {
 	 * @return a byte array of length 4
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public static byte[] intToBytes(int n) { return new byte[] { (byte) (n >>> 24), (byte) (n >>> 16), (byte) (n >>> 8), (byte) n }; }
+	public static byte[] intToBytes(int n) {
+		return new byte[] { (byte) (n >>> 24), (byte) (n >>> 16), (byte) (n >>> 8), (byte) n };
+	}
 
 	/**
 	 * Converts four bytes in byte array to an integer
@@ -30,8 +32,9 @@ public final class SerializationUtils {
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public static int bytesToInt(byte[] bytes, int offset) {
-		return (bytes[offset] & 0xFF) << 24 | (bytes[offset + 1] & 0xFF) << 16 | (bytes[offset + 2] & 0xFF) << 8
-				| (bytes[offset + 3] & 0xFF) << 0;
+		return (bytes[offset] & 0xFF) << 24 | (bytes[offset + 1] & 0xFF) << 16
+			| (bytes[offset + 2] & 0xFF) << 8
+			| (bytes[offset + 3] & 0xFF) << 0;
 	}
 
 	/**
@@ -41,14 +44,14 @@ public final class SerializationUtils {
 	 * @param file            the file to deserialize from
 	 * @param serializedClass the class of the object to deserialize
 	 * @return the deserialized object
-	 * @throws IOException            if something failed while deserializing the
-	 *                                object
-	 * @throws ClassNotFoundException if the deserialized object can not be linked
-	 *                                to a class
+	 * @throws IOException            if something failed while deserializing the object
+	 * @throws ClassNotFoundException if the deserialized object can not be linked to a class
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public static <T extends Serializable> T read(File file, Class<T> serializedClass) throws IOException, ClassNotFoundException {
-		if (file == null) throw new NullPointerException("File is null");
+	public static <T extends Serializable> T read(File file, Class<T> serializedClass)
+		throws IOException, ClassNotFoundException {
+		if (file == null)
+			throw new NullPointerException("File is null");
 		return read(new FileInputStream(file), serializedClass);
 	}
 
@@ -59,13 +62,12 @@ public final class SerializationUtils {
 	 * @param bytes           the array in which the serialized object is stored
 	 * @param serializedClass the class of the serialized object
 	 * @return the deserialized object
-	 * @throws IOException            if something failed while deserializing the
-	 *                                object
-	 * @throws ClassNotFoundException if the deserialized object can not be linked
-	 *                                to a class
+	 * @throws IOException            if something failed while deserializing the object
+	 * @throws ClassNotFoundException if the deserialized object can not be linked to a class
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public static <T extends Serializable> T read(byte[] bytes, Class<T> serializedClass) throws IOException, ClassNotFoundException {
+	public static <T extends Serializable> T read(byte[] bytes, Class<T> serializedClass)
+		throws IOException, ClassNotFoundException {
 		return read(new ByteArrayInputStream(bytes), serializedClass);
 	}
 
@@ -74,16 +76,14 @@ public final class SerializationUtils {
 	 *
 	 * @param <T>             the type of the serialized object
 	 * @param in              the {@link InputStream} of a serialized Object
-	 * @param serializedClass the object type to convert the deserialized object
-	 *                        into
+	 * @param serializedClass the object type to convert the deserialized object into
 	 * @return the deserialized object
-	 * @throws IOException            if something failed while deserializing the
-	 *                                object
-	 * @throws ClassNotFoundException if the deserialized object can not be linked
-	 *                                to a class
+	 * @throws IOException            if something failed while deserializing the object
+	 * @throws ClassNotFoundException if the deserialized object can not be linked to a class
 	 * @since Envoy Common v0.2-alpha
 	 */
-	public static <T extends Serializable> T read(InputStream in, Class<T> serializedClass) throws IOException, ClassNotFoundException {
+	public static <T extends Serializable> T read(InputStream in, Class<T> serializedClass)
+		throws IOException, ClassNotFoundException {
 		try (ObjectInputStream oin = new ObjectInputStream(in)) {
 			return serializedClass.cast(oin.readObject());
 		}
@@ -98,8 +98,10 @@ public final class SerializationUtils {
 	 * @since Envoy Common v0.2-alpha
 	 */
 	public static void write(File file, Object... objs) throws IOException {
-		if (file == null) throw new NullPointerException("File is null");
-		if (objs == null) throw new NullPointerException("Null array passed to serialize");
+		if (file == null)
+			throw new NullPointerException("File is null");
+		if (objs == null)
+			throw new NullPointerException("Null array passed to serialize");
 		if (!file.exists()) {
 			file.getParentFile().mkdirs();
 			file.createNewFile();
@@ -127,8 +129,8 @@ public final class SerializationUtils {
 	}
 
 	/**
-	 * Serializes an object and writes it into an output stream preceded by 4 bytes
-	 * containing the number of serialized bytes.
+	 * Serializes an object and writes it into an output stream preceded by 4 bytes containing the
+	 * number of serialized bytes.
 	 *
 	 * @param obj the object to serialize
 	 * @param out the output stream to serialize to
diff --git a/common/src/main/java/envoy/util/package-info.java b/common/src/main/java/envoy/util/package-info.java
index 4d8e716..8b5ebb2 100644
--- a/common/src/main/java/envoy/util/package-info.java
+++ b/common/src/main/java/envoy/util/package-info.java
@@ -1,7 +1,6 @@
 /**
- * This package contains general useful classes that can be used by both Envoy
- * Client and Envoy Server Standalone and that could not be assigned to any
- * other package.
+ * This package contains general useful classes that can be used by both Envoy Client and Envoy
+ * Server Standalone and that could not be assigned to any other package.
  *
  * @author Leon Hofmeister
  * @author Maximilian K&auml;fer
diff --git a/common/src/main/java/module-info.java b/common/src/main/java/module-info.java
index 3e6a4b5..b3fc531 100644
--- a/common/src/main/java/module-info.java
+++ b/common/src/main/java/module-info.java
@@ -1,6 +1,6 @@
 /**
- * This module contains all packages that are used by Envoy Client and Envoy
- * Server Standalone at the same time.
+ * This module contains all packages that are used by Envoy Client and Envoy Server Standalone at
+ * the same time.
  *
  * @author Leon Hofmeister
  * @author Maximilian K&auml;fer
diff --git a/common/src/test/java/envoy/data/UserTest.java b/common/src/test/java/envoy/data/UserTest.java
index 4a1688b..d8e65cd 100644
--- a/common/src/test/java/envoy/data/UserTest.java
+++ b/common/src/test/java/envoy/data/UserTest.java
@@ -26,7 +26,8 @@ class UserTest {
 		User	user3				= new User(3, "ai");
 		User	user4				= new User(4, "ki", Set.of(user2, user3));
 		User	user5				= new User(5, "ka", Set.of(user2, user3, user4));
-		User	user				= new User(1, "maxi", UserStatus.AWAY, Set.of(user2, user3, user4, user5));
+		User	user				=
+			new User(1, "maxi", UserStatus.AWAY, Set.of(user2, user3, user4, user5));
 		var		serializedUser		= SerializationUtils.writeToByteArray(user);
 		var		deserializedUser	= SerializationUtils.read(serializedUser, User.class);
 		assertEquals(user.getContacts(), deserializedUser.getContacts());
diff --git a/server/src/main/java/envoy/server/Startup.java b/server/src/main/java/envoy/server/Startup.java
index 6beafee..e34cf91 100755
--- a/server/src/main/java/envoy/server/Startup.java
+++ b/server/src/main/java/envoy/server/Startup.java
@@ -6,10 +6,11 @@ import java.util.logging.Level;
 
 import com.jenkov.nioserver.Server;
 
+import envoy.util.EnvoyLog;
+
 import envoy.server.data.*;
 import envoy.server.net.*;
 import envoy.server.processors.*;
-import envoy.util.EnvoyLog;
 
 /**
  * Starts the server.
@@ -27,8 +28,8 @@ public final class Startup {
 	/**
 	 * Starts the server.
 	 *
-	 * @param args the run configuration. If it is "no-enter-to-stop" at position 0,
-	 *             no command to read in an enter press will be generated
+	 * @param args the run configuration. If it is "no-enter-to-stop" at position 0, no command to
+	 *             read in an enter press will be generated
 	 * @throws IOException if the server crashes
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
@@ -37,31 +38,34 @@ public final class Startup {
 			config.loadAll(Startup.class, "server.properties", args);
 			EnvoyLog.initialize(config);
 		} catch (final IllegalStateException e) {
-			EnvoyLog.getLogger(Startup.class).log(Level.SEVERE, "Error loading configuration values: ", e);
+			EnvoyLog.getLogger(Startup.class).log(Level.SEVERE,
+				"Error loading configuration values: ", e);
 			System.exit(1);
 		}
 
 		final var server = new Server(8080, ObjectMessageReader::new,
-				new ObjectMessageProcessor(Set.of(new LoginCredentialProcessor(),
-						new MessageProcessor(),
-						new GroupMessageProcessor(),
-						new GroupCreationProcessor(),
-						new MessageStatusChangeProcessor(),
-						new GroupMessageStatusChangeProcessor(),
-						new UserStatusChangeProcessor(),
-						new IDGeneratorRequestProcessor(),
-						new UserSearchProcessor(),
-						new ContactOperationProcessor(),
-						new IsTypingProcessor(),
-						new NameChangeProcessor(),
-						new ProfilePicChangeProcessor(),
-						new PasswordChangeRequestProcessor(),
-						new IssueProposalProcessor())));
+			new ObjectMessageProcessor(Set.of(new LoginCredentialProcessor(),
+				new MessageProcessor(),
+				new GroupMessageProcessor(),
+				new GroupCreationProcessor(),
+				new MessageStatusChangeProcessor(),
+				new GroupMessageStatusChangeProcessor(),
+				new UserStatusChangeProcessor(),
+				new GroupResizeProcessor(),
+				new IDGeneratorRequestProcessor(),
+				new UserSearchProcessor(),
+				new UserOperationProcessor(),
+				new IsTypingProcessor(),
+				new NameChangeProcessor(),
+				new ProfilePicChangeProcessor(),
+				new PasswordChangeRequestProcessor(),
+				new IssueProposalProcessor())));
 
 		// Initialize the current message ID
 		final var persistenceManager = PersistenceManager.getInstance();
 		if (persistenceManager.getConfigItemByID("currentMessageId") == null)
-			persistenceManager.addConfigItem(new envoy.server.data.ConfigItem("currentMessageId", "0"));
+			persistenceManager
+				.addConfigItem(new envoy.server.data.ConfigItem("currentMessageId", "0"));
 
 		server.start();
 		server.getSocketProcessor().registerSocketIdListener(ConnectionManager.getInstance());
diff --git a/server/src/main/java/envoy/server/data/Contact.java b/server/src/main/java/envoy/server/data/Contact.java
index 36a302f..385afb9 100644
--- a/server/src/main/java/envoy/server/data/Contact.java
+++ b/server/src/main/java/envoy/server/data/Contact.java
@@ -6,8 +6,7 @@ import java.util.Set;
 import javax.persistence.*;
 
 /**
- * This class acts as a superclass for all contacts, being {@link User}s and
- * {@link Group}s.
+ * This class acts as a superclass for all contacts, being {@link User}s and {@link Group}s.
  *
  * @author Maximilian K&auml;fer
  * @since Envoy Server Standalone v0.1-alpha
@@ -30,18 +29,16 @@ public abstract class Contact {
 	protected Set<Contact> contacts;
 
 	/**
-	 * @return a {@link envoy.data.Contact} object of this envoy.server.data.Contact
-	 *         object.
+	 * @return a {@link envoy.data.Contact} object of this envoy.server.data.Contact object.
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
 	public abstract envoy.data.Contact toCommon();
 
 	/**
-	 * Transforms this contact into a {@link envoy.data.Contact} where the contacts
-	 * set of contacts is empty.
+	 * Transforms this contact into a {@link envoy.data.Contact} where the contacts set of contacts
+	 * is empty.
 	 *
-	 * @return a {@link envoy.data.Contact} object of this contact
-	 *         object.
+	 * @return a {@link envoy.data.Contact} object of this contact object.
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
 	protected abstract envoy.data.Contact toFlatCommon();
@@ -99,5 +96,8 @@ public abstract class Contact {
 	public void setCreationDate(Instant creationDate) { this.creationDate = creationDate; }
 
 	@Override
-	public String toString() { return String.format("%s[id=%d,name=%s,%d contact(s)]", getClass().getSimpleName(), id, name, contacts.size()); }
+	public String toString() {
+		return String.format("%s[id=%d,name=%s,%d contact(s)]", getClass().getSimpleName(), id,
+			name, contacts.size());
+	}
 }
diff --git a/server/src/main/java/envoy/server/data/Group.java b/server/src/main/java/envoy/server/data/Group.java
index f0ccb50..151159e 100644
--- a/server/src/main/java/envoy/server/data/Group.java
+++ b/server/src/main/java/envoy/server/data/Group.java
@@ -5,22 +5,16 @@ import java.util.stream.Collectors;
 import javax.persistence.*;
 
 /**
- * Represents a group inside the database. Referred to as "server group" as
- * opposed to "group" from Envoy Common.
+ * Represents a group inside the database. Referred to as "server group" as opposed to "group" from
+ * Envoy Common.
  *
  * @author Maximilian K&auml;fer
  * @since Envoy Server Standalone v0.1-alpha
  */
 @Entity
 @NamedQueries({
-	@NamedQuery(
-		name = Group.findByName,
-		query = "SELECT g FROM Group g WHERE g.name = :name"
-	),
-	@NamedQuery(
-		name = Group.findPendingGroups,
-		query = "SELECT g FROM Group g WHERE g.creationDate > :lastSeen AND :user MEMBER OF g.contacts"
-	)
+				@NamedQuery(name = Group.findByName, query = "SELECT g FROM Group g WHERE g.name = :name"),
+				@NamedQuery(name = Group.findPendingGroups, query = "SELECT g FROM Group g WHERE g.creationDate > :lastSeen AND :user MEMBER OF g.contacts")
 })
 public final class Group extends Contact {
 
@@ -32,7 +26,8 @@ public final class Group extends Contact {
 	public static final String findByName = "Group.findByName";
 
 	/**
-	 * Named query retrieving all pending groups for a specific user (parameter {@code :user}, {@code :lastSeen}).
+	 * Named query retrieving all pending groups for a specific user (parameter {@code :user},
+	 * {@code :lastSeen}).
 	 *
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
@@ -40,9 +35,12 @@ public final class Group extends Contact {
 
 	@Override
 	public envoy.data.Group toCommon() {
-		return new envoy.data.Group(id, name, contacts.parallelStream().map(User.class::cast).map(User::toFlatCommon).collect(Collectors.toSet()));
+		return new envoy.data.Group(id, name, contacts.parallelStream().map(User.class::cast)
+			.map(User::toFlatCommon).collect(Collectors.toSet()));
 	}
 
 	@Override
-	protected envoy.data.Group toFlatCommon() { return toCommon(); }
+	protected envoy.data.Group toFlatCommon() {
+		return toCommon();
+	}
 }
diff --git a/server/src/main/java/envoy/server/data/GroupMessage.java b/server/src/main/java/envoy/server/data/GroupMessage.java
index 444a935..717d7c8 100644
--- a/server/src/main/java/envoy/server/data/GroupMessage.java
+++ b/server/src/main/java/envoy/server/data/GroupMessage.java
@@ -12,20 +12,17 @@ import envoy.data.Group;
  * @since Envoy Server Standalone v0.1-beta
  */
 @Entity
-@NamedQuery(
-	name = GroupMessage.getPendingGroupMsg,
-	query = "SELECT m FROM GroupMessage m JOIN m.memberMessageStatus s WHERE KEY(s) = :userId AND (m.creationDate > :lastSeen "
-			+ "OR m.status = envoy.data.Message$MessageStatus.RECEIVED AND m.receivedDate > :lastSeen "
-			+ "OR m.status = envoy.data.Message$MessageStatus.READ AND m.readDate > :lastSeen "
-			+ "OR m.lastStatusChangeDate > :lastSeen)"
-)
+@NamedQuery(name = GroupMessage.getPendingGroupMsg, query = "SELECT m FROM GroupMessage m JOIN m.memberMessageStatus s WHERE KEY(s) = :userId AND (m.creationDate > :lastSeen "
+	+ "OR m.status = envoy.data.Message$MessageStatus.RECEIVED AND m.receivedDate > :lastSeen "
+	+ "OR m.status = envoy.data.Message$MessageStatus.READ AND m.readDate > :lastSeen "
+	+ "OR m.lastStatusChangeDate > :lastSeen)")
 public final class GroupMessage extends Message {
 
 	/**
-	 * Named query retrieving pending group messages sent to a group containing a
-	 * specific user (parameter {@code userId}) that were sent after a certain time
-	 * stamp (parameter {@code :lastSeen}).
-	 * 
+	 * Named query retrieving pending group messages sent to a group containing a specific user
+	 * (parameter {@code userId}) that were sent after a certain time stamp (parameter
+	 * {@code :lastSeen}).
+	 *
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
 	public static final String getPendingGroupMsg = "GroupMessage.getPendingGroupMsg";
@@ -46,9 +43,8 @@ public final class GroupMessage extends Message {
 	/**
 	 * Constructs a database groupMessage from a common groupMessage.
 	 *
-	 * @param groupMessage         the {@link envoy.data.GroupMessage} to convert
-	 *                             into a
-	 *                             database {@link GroupMessage}
+	 * @param groupMessage         the {@link envoy.data.GroupMessage} to convert into a database
+	 *                             {@link GroupMessage}
 	 * @param lastStatusChangeDate the time stamp to set
 	 * @since Envoy Server Standalone v0.2-beta
 	 */
@@ -59,29 +55,31 @@ public final class GroupMessage extends Message {
 	}
 
 	/**
-	 * Converts this groupMessage into an instance of
-	 * {@link envoy.data.GroupMessage}.
+	 * Converts this groupMessage into an instance of {@link envoy.data.GroupMessage}.
 	 *
-	 * @return a {@link envoy.data.GroupMessage} containing the same values as this
-	 *         groupMessage
+	 * @return a {@link envoy.data.GroupMessage} containing the same values as this groupMessage
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
 	@Override
 	public envoy.data.GroupMessage toCommon() {
-		return prepareBuilder().buildGroupMessage((Group) recipient.toCommon(), new HashMap<>(memberMessageStatus));
+		return prepareBuilder().buildGroupMessage((Group) recipient.toCommon(),
+			new HashMap<>(memberMessageStatus));
 	}
 
 	/**
 	 * @return the memberMessageStatus
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
-	public Map<Long, envoy.data.Message.MessageStatus> getMemberMessageStatus() { return memberMessageStatus; }
+	public Map<Long, envoy.data.Message.MessageStatus> getMemberMessageStatus() {
+		return memberMessageStatus;
+	}
 
 	/**
 	 * @param memberMessageStatus the memberMessageStatus to set
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
-	public void setMemberMessageStatus(Map<Long, envoy.data.Message.MessageStatus> memberMessageStatus) {
+	public void setMemberMessageStatus(
+		Map<Long, envoy.data.Message.MessageStatus> memberMessageStatus) {
 		this.memberMessageStatus = memberMessageStatus;
 	}
 
diff --git a/server/src/main/java/envoy/server/data/Message.java b/server/src/main/java/envoy/server/data/Message.java
index bd5f006..036c47a 100755
--- a/server/src/main/java/envoy/server/data/Message.java
+++ b/server/src/main/java/envoy/server/data/Message.java
@@ -12,14 +12,14 @@ import envoy.data.Attachment.AttachmentType;
 import envoy.data.Message.MessageStatus;
 
 /**
- * This JPA entity, which will be referred to as database message, stores the
- * information contained inside a {@link envoy.data.Message} inside the
- * database, while having a slightly different data layout.
+ * This JPA entity, which will be referred to as database message, stores the information contained
+ * inside a {@link envoy.data.Message} inside the database, while having a slightly different data
+ * layout.
  * <p>
  * A message can be converted to a database message by using the
- * {@link Message#Message(envoy.data.Message)} constructor. A database message
- * can be converted to a regular message using the {@link Message#toCommon()}
- * method. In both cases, the objects will not contain references to each other.
+ * {@link Message#Message(envoy.data.Message)} constructor. A database message can be converted to a
+ * regular message using the {@link Message#toCommon()} method. In both cases, the objects will not
+ * contain references to each other.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Server Standalone v0.1-alpha
@@ -27,22 +27,19 @@ import envoy.data.Message.MessageStatus;
 @Entity
 @Table(name = "messages")
 @Inheritance(strategy = InheritanceType.SINGLE_TABLE)
-@NamedQuery(
-	name = Message.getPending,
-	query = "SELECT m FROM Message m WHERE "
-			// Send to or by the user before last seen
-			+ "(m.sender = :user OR m.recipient = :user) AND m.creationDate > :lastSeen "
-			// SENT to the user
-			+ "OR m.recipient = :user AND m.status = envoy.data.Message$MessageStatus.SENT "
-			// Sent by the user and RECEIVED / READ after last seen
-			+ "OR m.sender = :user AND (m.status = envoy.data.Message$MessageStatus.RECEIVED AND m.receivedDate > :lastSeen "
-			+ "OR m.status = envoy.data.Message$MessageStatus.READ AND m.readDate > :lastSeen)"
-)
+@NamedQuery(name = Message.getPending, query = "SELECT m FROM Message m WHERE "
+	// Send to or by the user before last seen
+	+ "(m.sender = :user OR m.recipient = :user) AND m.creationDate > :lastSeen "
+	// SENT to the user
+	+ "OR m.recipient = :user AND m.status = envoy.data.Message$MessageStatus.SENT "
+	// Sent by the user and RECEIVED / READ after last seen
+	+ "OR m.sender = :user AND (m.status = envoy.data.Message$MessageStatus.RECEIVED AND m.receivedDate > :lastSeen "
+	+ "OR m.status = envoy.data.Message$MessageStatus.READ AND m.readDate > :lastSeen)")
 public class Message {
 
 	/**
-	 * Named query retrieving pending messages for a user (parameter {@code :user})
-	 * which was last seen after a specific date (parameter {@code :lastSeen}).
+	 * Named query retrieving pending messages for a user (parameter {@code :user}) which was last
+	 * seen after a specific date (parameter {@code :lastSeen}).
 	 *
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
@@ -51,11 +48,11 @@ public class Message {
 	@Id
 	protected long id;
 
-	@ManyToOne
+	@ManyToOne(cascade = CascadeType.REMOVE)
 	@JoinColumn
 	protected User sender;
 
-	@ManyToOne
+	@ManyToOne(cascade = CascadeType.REMOVE)
 	@JoinColumn
 	protected Contact recipient;
 
@@ -85,8 +82,7 @@ public class Message {
 	/**
 	 * Constructs a database message from a common message.
 	 *
-	 * @param message the {@link envoy.data.Message} to convert into a database
-	 *                {@link Message}
+	 * @param message the {@link envoy.data.Message} to convert into a database {@link Message}
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public Message(envoy.data.Message message) {
@@ -111,11 +107,12 @@ public class Message {
 	/**
 	 * Converts this message into an instance of {@link envoy.data.Message}.
 	 *
-	 * @return a {@link envoy.data.Message} containing the same values as this
-	 *         message
+	 * @return a {@link envoy.data.Message} containing the same values as this message
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public envoy.data.Message toCommon() { return prepareBuilder().build(); }
+	public envoy.data.Message toCommon() {
+		return prepareBuilder().build();
+	}
 
 	/**
 	 * @return a message builder containing the state of this message
@@ -128,13 +125,14 @@ public class Message {
 			.setReadDate(readDate)
 			.setStatus(status)
 			.setForwarded(forwarded);
-		if (attachment != null) builder.setAttachment(new Attachment(attachment, attachmentName, attachmentType));
+		if (attachment != null)
+			builder.setAttachment(new Attachment(attachment, attachmentName, attachmentType));
 		return builder;
 	}
 
 	/**
-	 * Sets the message status to {@link MessageStatus#RECEIVED} and sets the
-	 * current time stamp as the received date.
+	 * Sets the message status to {@link MessageStatus#RECEIVED} and sets the current time stamp as
+	 * the received date.
 	 *
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
@@ -144,8 +142,8 @@ public class Message {
 	}
 
 	/**
-	 * Sets the message status to {@link MessageStatus#READ} and sets the
-	 * current time stamp as the read date.
+	 * Sets the message status to {@link MessageStatus#READ} and sets the current time stamp as the
+	 * read date.
 	 *
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
@@ -207,8 +205,7 @@ public class Message {
 	public void setCreationDate(Instant creationDate) { this.creationDate = creationDate; }
 
 	/**
-	 * @return the date at which a {link envoy.data.Message} has been received by
-	 *         the server
+	 * @return the date at which a {link envoy.data.Message} has been received by the server
 	 * @since Envoy Server Standalone v0.2-beta
 	 */
 	public Instant getReceivedDate() { return receivedDate; }
@@ -279,7 +276,9 @@ public class Message {
 	 * @param attachmentType the attachmentType to set
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
-	public void setAttachmentType(AttachmentType attachmentType) { this.attachmentType = attachmentType; }
+	public void setAttachmentType(AttachmentType attachmentType) {
+		this.attachmentType = attachmentType;
+	}
 
 	/**
 	 * @return the attachmentName
@@ -291,7 +290,9 @@ public class Message {
 	 * @param attachmentName the attachmentName to set
 	 * @since Envoy Server v0.2-beta
 	 */
-	public void setAttachmentName(String attachmentName) { this.attachmentName = attachmentName; }
+	public void setAttachmentName(String attachmentName) {
+		this.attachmentName = attachmentName;
+	}
 
 	/**
 	 * @return whether this message is a forwarded message
diff --git a/server/src/main/java/envoy/server/data/PersistenceManager.java b/server/src/main/java/envoy/server/data/PersistenceManager.java
index 230dae8..ddabe7b 100755
--- a/server/src/main/java/envoy/server/data/PersistenceManager.java
+++ b/server/src/main/java/envoy/server/data/PersistenceManager.java
@@ -2,10 +2,13 @@ package envoy.server.data;
 
 import java.time.Instant;
 import java.util.List;
+import java.util.logging.Level;
 
 import javax.persistence.*;
 
 import envoy.data.User.UserStatus;
+import envoy.util.EnvoyLog;
+
 import envoy.server.net.ConnectionManager;
 
 /**
@@ -17,7 +20,8 @@ import envoy.server.net.ConnectionManager;
  */
 public final class PersistenceManager {
 
-	private final EntityManager		entityManager	= Persistence.createEntityManagerFactory("envoy").createEntityManager();
+	private final EntityManager		entityManager	=
+		Persistence.createEntityManagerFactory("envoy").createEntityManager();
 	private final EntityTransaction	transaction		= entityManager.getTransaction();
 
 	private static final PersistenceManager persistenceManager = new PersistenceManager();
@@ -33,7 +37,11 @@ public final class PersistenceManager {
 				.getOnlineUsers()
 				.stream()
 				.map(this::getUserByID)
-				.forEach(user -> { user.setStatus(UserStatus.OFFLINE); user.setLastSeen(Instant.now()); entityManager.merge(user); });
+				.forEach(user -> {
+					user.setStatus(UserStatus.OFFLINE);
+					user.setLastSeen(Instant.now());
+					entityManager.merge(user);
+				});
 		})));
 	}
 
@@ -49,7 +57,9 @@ public final class PersistenceManager {
 	 * @param contact the {@link Contact} to add to the database
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public void addContact(Contact contact) { persist(contact); }
+	public void addContact(Contact contact) {
+		persist(contact);
+	}
 
 	/**
 	 * Adds a {@link Message} to the database.
@@ -57,7 +67,9 @@ public final class PersistenceManager {
 	 * @param message the {@link Message} to add to the database
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public void addMessage(Message message) { persist(message); }
+	public void addMessage(Message message) {
+		persist(message);
+	}
 
 	/**
 	 * Adds a {@link ConfigItem} to the database.
@@ -65,7 +77,9 @@ public final class PersistenceManager {
 	 * @param configItem the {@link ConfigItem} to add to the database
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public void addConfigItem(ConfigItem configItem) { persist(configItem); }
+	public void addConfigItem(ConfigItem configItem) {
+		persist(configItem);
+	}
 
 	/**
 	 * Updates a {@link Contact} in the database
@@ -73,7 +87,9 @@ public final class PersistenceManager {
 	 * @param contact the {@link Contact} to add to the database
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public void updateContact(Contact contact) { merge(contact); }
+	public void updateContact(Contact contact) {
+		merge(contact);
+	}
 
 	/**
 	 * Updates a {@link Message} in the database.
@@ -81,7 +97,9 @@ public final class PersistenceManager {
 	 * @param message the message to update
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public void updateMessage(Message message) { merge(message); }
+	public void updateMessage(Message message) {
+		merge(message);
+	}
 
 	/**
 	 * Updates a {@link ConfigItem} in the database.
@@ -89,7 +107,9 @@ public final class PersistenceManager {
 	 * @param configItem the configItem to update
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public void updateConfigItem(ConfigItem configItem) { merge(configItem); }
+	public void updateConfigItem(ConfigItem configItem) {
+		merge(configItem);
+	}
 
 	/**
 	 * Deletes a {@link Contact} in the database.
@@ -97,7 +117,15 @@ public final class PersistenceManager {
 	 * @param contact the {@link Contact} to delete
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public void deleteContact(Contact contact) { remove(contact); }
+	public void deleteContact(Contact contact) {
+		transaction(() -> {
+
+			// Remove this contact from the contact list of his contacts
+			for (final var remainingContact : contact.getContacts())
+				remainingContact.getContacts().remove(contact);
+		});
+		remove(contact);
+	}
 
 	/**
 	 * Deletes a {@link Message} in the database.
@@ -105,7 +133,9 @@ public final class PersistenceManager {
 	 * @param message the {@link Message} to delete
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public void deleteMessage(Message message) { remove(message); }
+	public void deleteMessage(Message message) {
+		remove(message);
+	}
 
 	/**
 	 * Searches for a {@link User} with a specific ID.
@@ -114,7 +144,9 @@ public final class PersistenceManager {
 	 * @return the user with the specified ID or {@code null} if none was found
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public User getUserByID(long id) { return entityManager.find(User.class, id); }
+	public User getUserByID(long id) {
+		return entityManager.find(User.class, id);
+	}
 
 	/**
 	 * Searches for a {@link Group} with a specific ID.
@@ -123,7 +155,9 @@ public final class PersistenceManager {
 	 * @return the group with the specified ID or {@code null} if none was found
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
-	public Group getGroupByID(long id) { return entityManager.find(Group.class, id); }
+	public Group getGroupByID(long id) {
+		return entityManager.find(Group.class, id);
+	}
 
 	/**
 	 * Searches for a {@link Contact} with a specific ID.
@@ -132,7 +166,9 @@ public final class PersistenceManager {
 	 * @return the contact with the specified ID or {@code null} if none was found
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
-	public Contact getContactByID(long id) { return entityManager.find(Contact.class, id); }
+	public Contact getContactByID(long id) {
+		return entityManager.find(Contact.class, id);
+	}
 
 	/**
 	 * Searched for a {@link User} with a specific name.
@@ -142,7 +178,8 @@ public final class PersistenceManager {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public User getUserByName(String name) {
-		return (User) entityManager.createNamedQuery(User.findByName).setParameter("name", name).getSingleResult();
+		return (User) entityManager.createNamedQuery(User.findByName).setParameter("name", name)
+			.getSingleResult();
 	}
 
 	/**
@@ -153,7 +190,8 @@ public final class PersistenceManager {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public Group getGroupByName(String name) {
-		return (Group) entityManager.createNamedQuery(Group.findByName).setParameter("name", name).getSingleResult();
+		return (Group) entityManager.createNamedQuery(Group.findByName).setParameter("name", name)
+			.getSingleResult();
 	}
 
 	/**
@@ -163,18 +201,21 @@ public final class PersistenceManager {
 	 * @return the message with the specified ID or {@code null} if none is found
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public Message getMessageByID(long id) { return entityManager.find(Message.class, id); }
+	public Message getMessageByID(long id) {
+		return entityManager.find(Message.class, id);
+	}
 
 	/**
 	 * @param key the name of this {@link ConfigItem}
 	 * @return the {@link ConfigItem} with the given name
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public ConfigItem getConfigItemByID(String key) { return entityManager.find(ConfigItem.class, key); }
+	public ConfigItem getConfigItemByID(String key) {
+		return entityManager.find(ConfigItem.class, key);
+	}
 
 	/**
-	 * Returns all messages received while being offline or the ones that have
-	 * changed.
+	 * Returns all messages received while being offline or the ones that have changed.
 	 *
 	 * @param user     the user who wants to receive his unread messages
 	 * @param lastSync the time stamp of the last synchronization
@@ -182,17 +223,16 @@ public final class PersistenceManager {
 	 * @since Envoy Server Standalone v0.2-beta
 	 */
 	public List<Message> getPendingMessages(User user, Instant lastSync) {
-		return entityManager.createNamedQuery(Message.getPending).setParameter("user", user).setParameter("lastSeen", lastSync).getResultList();
+		return entityManager.createNamedQuery(Message.getPending).setParameter("user", user)
+			.setParameter("lastSeen", lastSync).getResultList();
 	}
 
 	/**
-	 * Returns all groupMessages received while being offline or the ones that have
-	 * changed.
+	 * Returns all groupMessages received while being offline or the ones that have changed.
 	 *
 	 * @param user     the user who wants to receive his unread groupMessages
 	 * @param lastSync the time stamp of the last synchronization
-	 * @return all groupMessages that the client does not yet have (unread
-	 *         groupMessages)
+	 * @return all groupMessages that the client does not yet have (unread groupMessages)
 	 * @since Envoy Server Standalone v0.2-beta
 	 */
 	public List<GroupMessage> getPendingGroupMessages(User user, Instant lastSync) {
@@ -203,12 +243,11 @@ public final class PersistenceManager {
 	}
 
 	/**
-	 * Searches for users matching a search phrase. Contacts of the attached user
-	 * and the attached user is ignored.
+	 * Searches for users matching a search phrase. Contacts of the attached user and the attached
+	 * user is ignored.
 	 *
 	 * @param searchPhrase the search phrase
-	 * @param userId       the ID of the user in whose context the search is
-	 *                     performed
+	 * @param userId       the ID of the user in whose context the search is performed
 	 * @return a list of all users who matched the criteria
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
@@ -227,17 +266,58 @@ public final class PersistenceManager {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public void addContactBidirectional(long contactID1, long contactID2) {
+		addContactBidirectional(getContactByID(contactID1), getContactByID(contactID2));
+	}
 
-		// Get users by ID
-		final var	c1	= getContactByID(contactID1);
-		final var	c2	= getContactByID(contactID2);
+	/**
+	 * Adds a contact to the contact list of another contact and vice versa.
+	 *
+	 * @param contact1 the first contact
+	 * @param contact2 the second contact
+	 * @since Envoy Server v0.3-beta
+	 */
+	public void addContactBidirectional(Contact contact1, Contact contact2) {
 
-		// Add users to each others contact lists
-		c1.getContacts().add(c2);
-		c2.getContacts().add(c1);
+		// Add users to each others contact list
+		contact1.getContacts().add(contact2);
+		contact2.getContacts().add(contact1);
 
 		// Synchronize changes with the database
-		transaction(() -> { entityManager.merge(c1); entityManager.merge(c2); });
+		transaction(() -> {
+			entityManager.merge(contact1);
+			entityManager.merge(contact2);
+		});
+	}
+
+	/**
+	 * Removes a contact from the contact list of another contact and vice versa.
+	 *
+	 * @param contactID1 the ID of the first contact
+	 * @param contactID2 the ID of the second contact
+	 * @since Envoy Server v0.3-beta
+	 */
+	public void removeContactBidirectional(long contactID1, long contactID2) {
+		removeContactBidirectional(getContactByID(contactID1), getContactByID(contactID2));
+	}
+
+	/**
+	 * Removes a contact from the contact list of another contact and vice versa.
+	 *
+	 * @param contact1 the first contact
+	 * @param contact2 the second contact
+	 * @since Envoy Server v0.3-beta
+	 */
+	public void removeContactBidirectional(Contact contact1, Contact contact2) {
+
+		// Remove users from each others contact list
+		contact1.getContacts().remove(contact2);
+		contact2.getContacts().remove(contact1);
+
+		// Synchronize changes with the database
+		transaction(() -> {
+			entityManager.merge(contact1);
+			entityManager.merge(contact2);
+		});
 	}
 
 	/**
@@ -246,21 +326,27 @@ public final class PersistenceManager {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public List<User> getContacts(User user) {
-		return entityManager.createNamedQuery(User.findContacts).setParameter("user", user).getResultList();
+		return entityManager.createNamedQuery(User.findContacts).setParameter("user", user)
+			.getResultList();
 	}
 
-	private void persist(Object obj) { transaction(() -> entityManager.persist(obj)); }
+	private void persist(Object obj) {
+		transaction(() -> entityManager.persist(obj));
+	}
 
-	private void merge(Object obj) { transaction(() -> entityManager.merge(obj)); }
+	private void merge(Object obj) {
+		transaction(() -> entityManager.merge(obj));
+	}
 
-	private void remove(Object obj) { transaction(() -> entityManager.remove(obj)); }
+	private void remove(Object obj) {
+		transaction(() -> entityManager.remove(obj));
+	}
 
 	/**
 	 * Performs a transaction with the given Runnable, that should somewhere call
 	 * {@link EntityManager}.
 	 *
-	 * @param entityManagerRelatedAction the action that changes something in the
-	 *                                   database
+	 * @param entityManagerRelatedAction the action that changes something in the database
 	 * @since Envoy Server v0.3-beta
 	 */
 	private void transaction(Runnable entityManagerRelatedAction) {
@@ -277,6 +363,16 @@ public final class PersistenceManager {
 				entityManagerRelatedAction.run();
 				transaction.commit();
 			}
+		} catch (final RollbackException e2) {
+
+			// Apparently a major problem exists. Discard faulty transaction and then go on.
+			if (transaction.isActive()) {
+				transaction.rollback();
+				EnvoyLog.getLogger(PersistenceManager.class)
+					.log(Level.SEVERE,
+						"Could not perform transaction, hence discarding it. It's likely that a serious issue exists.");
+			} else
+				throw e2;
 		}
 	}
 }
diff --git a/server/src/main/java/envoy/server/data/ServerConfig.java b/server/src/main/java/envoy/server/data/ServerConfig.java
index 96f4d01..5611eef 100644
--- a/server/src/main/java/envoy/server/data/ServerConfig.java
+++ b/server/src/main/java/envoy/server/data/ServerConfig.java
@@ -16,7 +16,9 @@ public final class ServerConfig extends Config {
 	 * @return the singleton instance of the server config
 	 * @since Envoy Client v0.1-beta
 	 */
-	public static ServerConfig getInstance() { return config == null ? config = new ServerConfig() : config; }
+	public static ServerConfig getInstance() {
+		return config == null ? config = new ServerConfig() : config;
+	}
 
 	private ServerConfig() {
 		super(".envoy-server");
@@ -45,13 +47,17 @@ public final class ServerConfig extends Config {
 	 * @return {@code true} if issue reporting is enabled
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public Boolean isIssueReportingEnabled() { return (Boolean) items.get("enableIssueReporting").get(); }
+	public Boolean isIssueReportingEnabled() {
+		return (Boolean) items.get("enableIssueReporting").get();
+	}
 
 	/**
 	 * @return {@code true} if attachment support has been enabled
 	 * @since Envoy Client v0.3-alpha
 	 */
-	public Boolean isAttachmentSupportEnabled() { return (Boolean) items.get("enableAttachments").get(); }
+	public Boolean isAttachmentSupportEnabled() {
+		return (Boolean) items.get("enableAttachments").get();
+	}
 
 	/**
 	 * @return {@code true} if group support has been enabled
@@ -85,9 +91,8 @@ public final class ServerConfig extends Config {
 
 	/**
 	 * @return the authorization token used to authenticate to
-	 *         {@link ServerConfig#getIssueReportingURL()}. If null,
-	 *         authorization is expected to occur via a query_param or via a basic
-	 *         user-password-combination
+	 *         {@link ServerConfig#getIssueReportingURL()}. If null, authorization is expected to
+	 *         occur via a query_param or via a basic user-password-combination
 	 * @since Envoy Server v0.2-beta
 	 */
 	public String getIssueAuthToken() { return (String) items.get("issueAuthToken").get(); }
@@ -96,5 +101,7 @@ public final class ServerConfig extends Config {
 	 * @return the amount of days after which user authentication tokens expire
 	 * @since Envoy Server v0.2-beta
 	 */
-	public Integer getAuthTokenExpiration() { return (Integer) items.get("authTokenExpiration").get(); }
+	public Integer getAuthTokenExpiration() {
+		return (Integer) items.get("authTokenExpiration").get();
+	}
 }
diff --git a/server/src/main/java/envoy/server/data/User.java b/server/src/main/java/envoy/server/data/User.java
index e4c0829..923a790 100755
--- a/server/src/main/java/envoy/server/data/User.java
+++ b/server/src/main/java/envoy/server/data/User.java
@@ -9,9 +9,9 @@ import javax.persistence.*;
 import envoy.data.User.UserStatus;
 
 /**
- * This class enables the storage of user specific data inside a database using
- * Hibernate. Its objects will be referred to as database users as opposed to
- * the common user objects present on both the client and the server.
+ * This class enables the storage of user specific data inside a database using Hibernate. Its
+ * objects will be referred to as database users as opposed to the common user objects present on
+ * both the client and the server.
  *
  * @author Kai S. K. Engelbart
  * @author Maximilian K&auml;fer
@@ -19,18 +19,9 @@ import envoy.data.User.UserStatus;
  */
 @Entity
 @NamedQueries({
-	@NamedQuery(
-		name = User.findByName,
-		query = "SELECT u FROM User u WHERE u.name = :name"
-	),
-	@NamedQuery(
-		name = User.findContacts,
-		query = "SELECT u.contacts FROM User u WHERE u = :user"
-	),
-	@NamedQuery(
-		name = User.searchByName,
-		query = "SELECT u FROM User u WHERE (lower(u.name) LIKE lower(:searchPhrase) AND u <> :context AND :context NOT MEMBER OF u.contacts)"
-	)
+				@NamedQuery(name = User.findByName, query = "SELECT u FROM User u WHERE u.name = :name"),
+				@NamedQuery(name = User.findContacts, query = "SELECT u.contacts FROM User u WHERE u = :user"),
+				@NamedQuery(name = User.searchByName, query = "SELECT u FROM User u WHERE (lower(u.name) LIKE lower(:searchPhrase) AND u <> :context AND :context NOT MEMBER OF u.contacts)")
 })
 public final class User extends Contact {
 
@@ -42,8 +33,7 @@ public final class User extends Contact {
 	public static final String findByName = "User.findByName";
 
 	/**
-	 * Named query retrieving the contacts of a given user (parameter
-	 * {@code :user}).
+	 * Named query retrieving the contacts of a given user (parameter {@code :user}).
 	 *
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
@@ -51,8 +41,8 @@ public final class User extends Contact {
 
 	/**
 	 * Named query searching for users with a name like a search phrase (parameter
-	 * {@code :searchPhrase}) that are not in the contact list of a given user
-	 * (parameter {@code :context}).
+	 * {@code :searchPhrase}) that are not in the contact list of a given user (parameter
+	 * {@code :context}).
 	 *
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
@@ -70,15 +60,21 @@ public final class User extends Contact {
 	@Column(name = "last_seen")
 	private Instant lastSeen;
 
+	@Column(name = "latest_contact_deletion")
+	private Instant latestContactDeletion;
+
 	private UserStatus status;
 
 	@Override
 	public envoy.data.User toCommon() {
-		return new envoy.data.User(id, name, status, contacts.parallelStream().map(Contact::toFlatCommon).collect(Collectors.toSet()));
+		return new envoy.data.User(id, name, status,
+			contacts.parallelStream().map(Contact::toFlatCommon).collect(Collectors.toSet()));
 	}
 
 	@Override
-	protected envoy.data.User toFlatCommon() { return new envoy.data.User(id, name, status, Set.of()); }
+	protected envoy.data.User toFlatCommon() {
+		return new envoy.data.User(id, name, status, Set.of());
+	}
 
 	/**
 	 * @return the password hash
@@ -111,11 +107,12 @@ public final class User extends Contact {
 	public Instant getAuthTokenExpiration() { return authTokenExpiration; }
 
 	/**
-	 * @param authTokenExpiration the authentication token expiration timestamp to
-	 *                            set
+	 * @param authTokenExpiration the authentication token expiration timestamp to set
 	 * @since Envoy Server v0.2-beta
 	 */
-	public void setAuthTokenExpiration(Instant authTokenExpiration) { this.authTokenExpiration = authTokenExpiration; }
+	public void setAuthTokenExpiration(Instant authTokenExpiration) {
+		this.authTokenExpiration = authTokenExpiration;
+	}
 
 	/**
 	 * @return the last date the user has been online
@@ -140,4 +137,18 @@ public final class User extends Contact {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public void setStatus(UserStatus status) { this.status = status; }
+
+	/**
+	 * @return the latestContactDeletion
+	 * @since Envoy Server v0.3-beta
+	 */
+	public Instant getLatestContactDeletion() { return latestContactDeletion; }
+
+	/**
+	 * @param latestContactDeletion the latestContactDeletion to set
+	 * @since Envoy Server v0.3-beta
+	 */
+	public void setLatestContactDeletion(Instant latestContactDeletion) {
+		this.latestContactDeletion = latestContactDeletion;
+	}
 }
diff --git a/server/src/main/java/envoy/server/net/ConnectionManager.java b/server/src/main/java/envoy/server/net/ConnectionManager.java
index 581a10f..4a8ea2c 100755
--- a/server/src/main/java/envoy/server/net/ConnectionManager.java
+++ b/server/src/main/java/envoy/server/net/ConnectionManager.java
@@ -7,6 +7,7 @@ import java.util.stream.Collectors;
 import com.jenkov.nioserver.ISocketIdListener;
 
 import envoy.data.User.UserStatus;
+
 import envoy.server.data.*;
 import envoy.server.processors.UserStatusChangeProcessor;
 
@@ -17,8 +18,8 @@ import envoy.server.processors.UserStatusChangeProcessor;
 public final class ConnectionManager implements ISocketIdListener {
 
 	/**
-	 * Contains all socket IDs that have not yet performed a handshake / acquired
-	 * their corresponding user ID.
+	 * Contains all socket IDs that have not yet performed a handshake / acquired their
+	 * corresponding user ID.
 	 *
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
@@ -46,7 +47,8 @@ public final class ConnectionManager implements ISocketIdListener {
 		if (!pendingSockets.remove(socketID)) {
 
 			// Notify contacts of this users offline-going
-			final envoy.server.data.User user = PersistenceManager.getInstance().getUserByID(getUserIDBySocketID(socketID));
+			final envoy.server.data.User user =
+				PersistenceManager.getInstance().getUserByID(getUserIDBySocketID(socketID));
 			user.setLastSeen(Instant.now());
 			UserStatusChangeProcessor.updateUserStatus(user, UserStatus.OFFLINE);
 
@@ -56,7 +58,9 @@ public final class ConnectionManager implements ISocketIdListener {
 	}
 
 	@Override
-	public void socketRegistered(long socketID) { pendingSockets.add(socketID); }
+	public void socketRegistered(long socketID) {
+		pendingSockets.add(socketID);
+	}
 
 	/**
 	 * Associates a socket ID with a user ID.
@@ -75,7 +79,9 @@ public final class ConnectionManager implements ISocketIdListener {
 	 * @return the ID of the socket
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public long getSocketID(long userID) { return sockets.get(userID); }
+	public long getSocketID(long userID) {
+		return sockets.get(userID);
+	}
 
 	/**
 	 * @param socketID the id of the socket whose User is needed
@@ -83,7 +89,8 @@ public final class ConnectionManager implements ISocketIdListener {
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public long getUserIDBySocketID(long socketID) {
-		return sockets.entrySet().stream().filter(entry -> entry.getValue().equals(socketID)).findFirst().get().getKey();
+		return sockets.entrySet().stream().filter(entry -> entry.getValue().equals(socketID))
+			.findFirst().get().getKey();
 	}
 
 	/**
@@ -91,7 +98,9 @@ public final class ConnectionManager implements ISocketIdListener {
 	 * @return {@code true} if the user is online
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public boolean isOnline(long userID) { return sockets.containsKey(userID); }
+	public boolean isOnline(long userID) {
+		return sockets.containsKey(userID);
+	}
 
 	/**
 	 * @return the userIDs of all users who are currently online
@@ -105,6 +114,7 @@ public final class ConnectionManager implements ISocketIdListener {
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
 	public Set<Long> getOnlineUsersOfGroup(Group group) {
-		return group.getContacts().stream().map(Contact::getID).filter(this::isOnline).collect(Collectors.toSet());
+		return group.getContacts().stream().map(Contact::getID).filter(this::isOnline)
+			.collect(Collectors.toSet());
 	}
 }
diff --git a/server/src/main/java/envoy/server/net/ObjectMessageProcessor.java b/server/src/main/java/envoy/server/net/ObjectMessageProcessor.java
index 876b6ac..0148be7 100755
--- a/server/src/main/java/envoy/server/net/ObjectMessageProcessor.java
+++ b/server/src/main/java/envoy/server/net/ObjectMessageProcessor.java
@@ -7,9 +7,10 @@ import java.util.logging.*;
 
 import com.jenkov.nioserver.*;
 
-import envoy.server.processors.ObjectProcessor;
 import envoy.util.EnvoyLog;
 
+import envoy.server.processors.ObjectProcessor;
+
 /**
  * Handles incoming objects.
  *
@@ -28,12 +29,16 @@ public final class ObjectMessageProcessor implements IMessageProcessor {
 	 * @param processors the {@link ObjectProcessor} to set
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public ObjectMessageProcessor(Set<ObjectProcessor<?>> processors) { this.processors = processors; }
+	public ObjectMessageProcessor(Set<ObjectProcessor<?>> processors) {
+		this.processors = processors;
+	}
 
 	@SuppressWarnings("unchecked")
 	@Override
 	public void process(Message message, WriteProxy writeProxy) {
-		try (ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(message.sharedArray, message.offset + 4, message.length - 4))) {
+		try (ObjectInputStream in =
+			new ObjectInputStream(new ByteArrayInputStream(message.sharedArray, message.offset + 4,
+				message.length - 4))) {
 			Object obj = in.readObject();
 			if (obj == null) {
 				logger.warning("Received a null object");
@@ -45,7 +50,8 @@ public final class ObjectMessageProcessor implements IMessageProcessor {
 			// Get processor and input class and process object
 			for (@SuppressWarnings("rawtypes")
 			ObjectProcessor p : processors) {
-				Class<?> c = (Class<?>) ((ParameterizedType) p.getClass().getGenericInterfaces()[0]).getActualTypeArguments()[0];
+				Class<?> c = (Class<?>) ((ParameterizedType) p.getClass().getGenericInterfaces()[0])
+					.getActualTypeArguments()[0];
 				if (c.equals(obj.getClass()))
 					try {
 						p.process(c.cast(obj), message.socketId, new ObjectWriteProxy(writeProxy));
diff --git a/server/src/main/java/envoy/server/net/ObjectMessageReader.java b/server/src/main/java/envoy/server/net/ObjectMessageReader.java
index a86c589..41e4660 100755
--- a/server/src/main/java/envoy/server/net/ObjectMessageReader.java
+++ b/server/src/main/java/envoy/server/net/ObjectMessageReader.java
@@ -16,9 +16,9 @@ import envoy.util.SerializationUtils;
  */
 public final class ObjectMessageReader implements IMessageReader {
 
-	private List<Message>	completeMessages	= new ArrayList<>();
-	private Message			nextMessage;
-	private MessageBuffer	messageBuffer;
+	private final List<Message>	completeMessages	= new ArrayList<>();
+	private Message				nextMessage;
+	private MessageBuffer		messageBuffer;
 
 	@Override
 	public List<Message> getMessages() { return completeMessages; }
@@ -43,7 +43,8 @@ public final class ObjectMessageReader implements IMessageReader {
 		buffer.clear();
 
 		// Get message length
-		if (nextMessage.length < 4) return;
+		if (nextMessage.length < 4)
+			return;
 		int length = SerializationUtils.bytesToInt(nextMessage.sharedArray, nextMessage.offset) + 4;
 		do {
 
@@ -58,7 +59,8 @@ public final class ObjectMessageReader implements IMessageReader {
 			}
 
 			// Get message length
-			if (nextMessage.length < 4) return;
+			if (nextMessage.length < 4)
+				return;
 			length = SerializationUtils.bytesToInt(nextMessage.sharedArray, nextMessage.offset) + 4;
 
 		} while (nextMessage.length >= length);
diff --git a/server/src/main/java/envoy/server/net/ObjectWriteProxy.java b/server/src/main/java/envoy/server/net/ObjectWriteProxy.java
index 53f12fc..61795c7 100755
--- a/server/src/main/java/envoy/server/net/ObjectWriteProxy.java
+++ b/server/src/main/java/envoy/server/net/ObjectWriteProxy.java
@@ -7,9 +7,10 @@ import java.util.stream.Stream;
 
 import com.jenkov.nioserver.*;
 
-import envoy.server.data.Contact;
 import envoy.util.*;
 
+import envoy.server.data.Contact;
+
 /**
  * This class defines methods to send an object to a client.
  *
@@ -21,7 +22,8 @@ public final class ObjectWriteProxy {
 	private final WriteProxy writeProxy;
 
 	private static final ConnectionManager	connectionManager	= ConnectionManager.getInstance();
-	private static final Logger				logger				= EnvoyLog.getLogger(ObjectWriteProxy.class);
+	private static final Logger				logger				=
+		EnvoyLog.getLogger(ObjectWriteProxy.class);
 
 	/**
 	 * Creates an instance of {@link ObjectWriteProxy}.
@@ -29,13 +31,14 @@ public final class ObjectWriteProxy {
 	 * @param writeProxy the {@link WriteProxy} to write objects to another client
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public ObjectWriteProxy(WriteProxy writeProxy) { this.writeProxy = writeProxy; }
+	public ObjectWriteProxy(WriteProxy writeProxy) {
+		this.writeProxy = writeProxy;
+	}
 
 	/**
 	 * @param recipientSocketID the socket id of the recipient
 	 * @param obj               the object to return to the client
-	 * @throws RuntimeException if the serialization of the object failed (this is
-	 *                          highly unlikely)
+	 * @throws RuntimeException if the serialization of the object failed (this is highly unlikely)
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	public void write(long recipientSocketID, Object obj) {
@@ -67,7 +70,9 @@ public final class ObjectWriteProxy {
 	 * @param message  the object to send
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
-	public void writeToOnlineContacts(Set<? extends Contact> contacts, Object message) { writeToOnlineContacts(contacts.stream(), message); }
+	public void writeToOnlineContacts(Set<? extends Contact> contacts, Object message) {
+		writeToOnlineContacts(contacts.stream(), message);
+	}
 
 	/**
 	 * Sends an object to all contacts in a set that are online.
@@ -77,6 +82,7 @@ public final class ObjectWriteProxy {
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
 	public void writeToOnlineContacts(Stream<? extends Contact> contacts, Object message) {
-		contacts.map(Contact::getID).filter(connectionManager::isOnline).map(connectionManager::getSocketID).forEach(id -> write(id, message));
+		contacts.map(Contact::getID).filter(connectionManager::isOnline)
+			.map(connectionManager::getSocketID).forEach(id -> write(id, message));
 	}
 }
diff --git a/server/src/main/java/envoy/server/processors/ContactOperationProcessor.java b/server/src/main/java/envoy/server/processors/ContactOperationProcessor.java
deleted file mode 100755
index 178bff4..0000000
--- a/server/src/main/java/envoy/server/processors/ContactOperationProcessor.java
+++ /dev/null
@@ -1,39 +0,0 @@
-package envoy.server.processors;
-
-import java.util.logging.Logger;
-
-import envoy.event.ElementOperation;
-import envoy.event.contact.ContactOperation;
-import envoy.server.data.PersistenceManager;
-import envoy.server.net.*;
-import envoy.util.EnvoyLog;
-
-/**
- * @author Kai S. K. Engelbart
- * @since Envoy Server Standalone v0.1-alpha
- */
-public final class ContactOperationProcessor implements ObjectProcessor<ContactOperation> {
-
-	private static final ConnectionManager connectionManager = ConnectionManager.getInstance();
-	private static final Logger				logger				= EnvoyLog.getLogger(ContactOperationProcessor.class);
-
-	@Override
-	public void process(ContactOperation evt, long socketId, ObjectWriteProxy writeProxy) {
-		switch (evt.getOperationType()) {
-			case ADD:
-				final long userID = ConnectionManager.getInstance().getUserIDBySocketID(socketId);
-				final long contactId = evt.get().getID();
-
-				logger.fine(String.format("Adding user %s to the contact list of user %d.%n", evt.get(), userID));
-				PersistenceManager.getInstance().addContactBidirectional(userID, contactId);
-
-				// Notify the contact if online
-				if (ConnectionManager.getInstance().isOnline(contactId))
-					writeProxy.write(connectionManager.getSocketID(contactId),
-							new ContactOperation(PersistenceManager.getInstance().getUserByID(userID).toCommon(), ElementOperation.ADD));
-				break;
-			default:
-				logger.warning(String.format("Received %s with an unsupported operation.", evt));
-		}
-	}
-}
diff --git a/server/src/main/java/envoy/server/processors/GroupCreationProcessor.java b/server/src/main/java/envoy/server/processors/GroupCreationProcessor.java
index 8f40af2..ac11131 100644
--- a/server/src/main/java/envoy/server/processors/GroupCreationProcessor.java
+++ b/server/src/main/java/envoy/server/processors/GroupCreationProcessor.java
@@ -5,8 +5,8 @@ import static envoy.server.Startup.config;
 import java.util.HashSet;
 
 import envoy.event.*;
-import envoy.event.contact.ContactOperation;
-import envoy.server.data.*;
+
+import envoy.server.data.PersistenceManager;
 import envoy.server.net.*;
 
 /**
@@ -21,21 +21,21 @@ public final class GroupCreationProcessor implements ObjectProcessor<GroupCreati
 	@Override
 	public void process(GroupCreation groupCreation, long socketID, ObjectWriteProxy writeProxy) {
 		// Don't allow the creation of groups if manually disabled
-		writeProxy.write(socketID, new GroupCreationResult(config.isGroupSupportEnabled()));
-		if (!config.isGroupSupportEnabled()) return;
+		if (!config.isGroupSupportEnabled()) {
+			writeProxy.write(socketID, new GroupCreationResult());
+			return;
+		}
 		final envoy.server.data.Group group = new envoy.server.data.Group();
 		group.setName(groupCreation.get());
 		group.setContacts(new HashSet<>());
-		groupCreation.getInitialMemberIDs().stream().map(persistenceManager::getUserByID).forEach(group.getContacts()::add);
-		group.getContacts().add(persistenceManager.getContactByID(connectionManager.getUserIDBySocketID(socketID)));
-		group.getContacts().forEach(c -> c.getContacts().add(group));
-		group.getContacts().add(persistenceManager.getUserByID(connectionManager.getUserIDBySocketID(socketID)));
 		persistenceManager.addContact(group);
-		group.getContacts()
+		groupCreation.getInitialMemberIDs()
 			.stream()
-			.map(Contact::getID)
-			.filter(connectionManager::isOnline)
-			.map(connectionManager::getSocketID)
-			.forEach(memberSocketID -> writeProxy.write(memberSocketID, new ContactOperation(group.toCommon(), ElementOperation.ADD)));
+			.map(persistenceManager::getUserByID)
+			.forEach(member -> persistenceManager.addContactBidirectional(member, group));
+		persistenceManager.addContactBidirectional(
+			persistenceManager.getUserByID(connectionManager.getUserIDBySocketID(socketID)), group);
+		writeProxy.writeToOnlineContacts(group.getContacts(),
+			new GroupCreationResult(group.toCommon()));
 	}
 }
diff --git a/server/src/main/java/envoy/server/processors/GroupMessageProcessor.java b/server/src/main/java/envoy/server/processors/GroupMessageProcessor.java
index 77ab232..a3b5747 100644
--- a/server/src/main/java/envoy/server/processors/GroupMessageProcessor.java
+++ b/server/src/main/java/envoy/server/processors/GroupMessageProcessor.java
@@ -11,9 +11,10 @@ import javax.persistence.EntityExistsException;
 
 import envoy.data.GroupMessage;
 import envoy.event.*;
+import envoy.util.EnvoyLog;
+
 import envoy.server.data.PersistenceManager;
 import envoy.server.net.*;
-import envoy.util.EnvoyLog;
 
 /**
  * @author Maximilian K&auml;fer
@@ -23,14 +24,16 @@ public final class GroupMessageProcessor implements ObjectProcessor<GroupMessage
 
 	private static final ConnectionManager	connectionManager	= ConnectionManager.getInstance();
 	private static final PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
-	private static final Logger				logger				= EnvoyLog.getLogger(GroupCreationProcessor.class);
+	private static final Logger				logger				=
+		EnvoyLog.getLogger(GroupCreationProcessor.class);
 
 	@Override
 	public void process(GroupMessage groupMessage, long socketID, ObjectWriteProxy writeProxy) {
 		groupMessage.nextStatus();
 
 		// Update statuses to SENT / RECEIVED depending on online status
-		groupMessage.getMemberStatuses().replaceAll((memberID, status) -> connectionManager.isOnline(memberID) ? RECEIVED : SENT);
+		groupMessage.getMemberStatuses().replaceAll(
+			(memberID, status) -> connectionManager.isOnline(memberID) ? RECEIVED : SENT);
 
 		// Set status for sender to READ
 		groupMessage.getMemberStatuses().replace(groupMessage.getSenderID(), READ);
@@ -44,7 +47,8 @@ public final class GroupMessageProcessor implements ObjectProcessor<GroupMessage
 		}
 
 		// message attachment will be automatically removed if disabled in config
-		final var groupMessageServer = new envoy.server.data.GroupMessage(groupMessage, Instant.now());
+		final var groupMessageServer =
+			new envoy.server.data.GroupMessage(groupMessage, Instant.now());
 		// Telling the server to reload the message without the attachment and telling
 		// the client not to send anymore attachments
 		if (!config.isAttachmentSupportEnabled() && groupMessage.hasAttachment()) {
@@ -57,11 +61,11 @@ public final class GroupMessageProcessor implements ObjectProcessor<GroupMessage
 		final var groupMessageCopy = groupMessage;
 		// Deliver the message to the recipients that are online
 		writeProxy.writeToOnlineContacts(
-				persistenceManager.getGroupByID(groupMessageCopy.getRecipientID())
-					.getContacts()
-					.stream()
-					.filter(c -> c.getID() != groupMessageCopy.getSenderID()),
-				groupMessageCopy);
+			persistenceManager.getGroupByID(groupMessageCopy.getRecipientID())
+				.getContacts()
+				.stream()
+				.filter(c -> c.getID() != groupMessageCopy.getSenderID()),
+			groupMessageCopy);
 
 		try {
 			PersistenceManager.getInstance().addMessage(groupMessageServer);
diff --git a/server/src/main/java/envoy/server/processors/GroupMessageStatusChangeProcessor.java b/server/src/main/java/envoy/server/processors/GroupMessageStatusChangeProcessor.java
index 2604698..5cbb883 100644
--- a/server/src/main/java/envoy/server/processors/GroupMessageStatusChangeProcessor.java
+++ b/server/src/main/java/envoy/server/processors/GroupMessageStatusChangeProcessor.java
@@ -8,22 +8,26 @@ import java.util.logging.*;
 
 import envoy.data.Message.MessageStatus;
 import envoy.event.*;
+import envoy.util.EnvoyLog;
+
 import envoy.server.data.*;
 import envoy.server.net.*;
-import envoy.util.EnvoyLog;
 
 /**
  * @author Maximilian K&auml;fer
  * @since Envoy Server Standalone v0.1-beta
  */
-public final class GroupMessageStatusChangeProcessor implements ObjectProcessor<GroupMessageStatusChange> {
+public final class GroupMessageStatusChangeProcessor
+	implements ObjectProcessor<GroupMessageStatusChange> {
 
 	private static final ConnectionManager	connectionManager	= ConnectionManager.getInstance();
 	private static final PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
-	private static final Logger				logger				= EnvoyLog.getLogger(MessageStatusChangeProcessor.class);
+	private static final Logger				logger				=
+		EnvoyLog.getLogger(MessageStatusChangeProcessor.class);
 
 	@Override
-	public void process(GroupMessageStatusChange statusChange, long socketID, ObjectWriteProxy writeProxy) {
+	public void process(GroupMessageStatusChange statusChange, long socketID,
+		ObjectWriteProxy writeProxy) {
 		GroupMessage gmsg = (GroupMessage) persistenceManager.getMessageByID(statusChange.getID());
 
 		// Any other status than READ is not supposed to be sent to the server
@@ -51,7 +55,7 @@ public final class GroupMessageStatusChangeProcessor implements ObjectProcessor<
 
 			// Notify online members about the status change
 			writeProxy.writeToOnlineContacts(gmsg.getRecipient().getContacts(),
-					new MessageStatusChange(gmsg.getID(), gmsg.getStatus(), Instant.now()));
+				new MessageStatusChange(gmsg.getID(), gmsg.getStatus(), Instant.now()));
 		}
 		persistenceManager.updateMessage(gmsg);
 	}
diff --git a/server/src/main/java/envoy/server/processors/GroupResizeProcessor.java b/server/src/main/java/envoy/server/processors/GroupResizeProcessor.java
index 0a5b697..9c42d3d 100644
--- a/server/src/main/java/envoy/server/processors/GroupResizeProcessor.java
+++ b/server/src/main/java/envoy/server/processors/GroupResizeProcessor.java
@@ -1,8 +1,13 @@
 package envoy.server.processors;
 
+import java.time.Instant;
+import java.util.logging.Level;
+
 import envoy.event.GroupResize;
+import envoy.util.EnvoyLog;
+
 import envoy.server.data.*;
-import envoy.server.net.*;
+import envoy.server.net.ObjectWriteProxy;
 
 /**
  * @author Maximilian K&auml;fer
@@ -10,35 +15,41 @@ import envoy.server.net.*;
  */
 public final class GroupResizeProcessor implements ObjectProcessor<GroupResize> {
 
-	private static final PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
-	private static final ConnectionManager	connectionManager	= ConnectionManager.getInstance();
+	private static final PersistenceManager persistenceManager = PersistenceManager.getInstance();
 
 	@Override
 	public void process(GroupResize groupResize, long socketID, ObjectWriteProxy writeProxy) {
 
 		// Acquire the group to resize from the database
-		var group = persistenceManager.getGroupByID(groupResize.getGroupID());
+		final var	group	= persistenceManager.getGroupByID(groupResize.getGroupID());
+		final var	sender	= persistenceManager.getUserByID(groupResize.get().getID());
 
 		// Perform the desired operation
 		switch (groupResize.getOperation()) {
 			case ADD:
-				group.getContacts().add(persistenceManager.getUserByID(groupResize.get().getID()));
-				break;
+				persistenceManager.addContactBidirectional(sender, group);
+				writeProxy.writeToOnlineContacts(group.getContacts(), group.toCommon());
+				return;
 			case REMOVE:
-				group.getContacts().remove(persistenceManager.getUserByID(groupResize.get().getID()));
-				break;
+				persistenceManager.removeContactBidirectional(sender, group);
+				sender.setLatestContactDeletion(Instant.now());
+
+				// The group has no more members and hence will be deleted
+				if (group.getContacts().isEmpty()) {
+					EnvoyLog.getLogger(GroupResizeProcessor.class).log(Level.INFO,
+						"Deleting now empty group " + group.getName());
+					persistenceManager.deleteContact(group);
+				} else {
+
+					// Informing the other members
+					writeProxy.writeToOnlineContacts(group.getContacts(), groupResize);
+					group.getContacts()
+						.forEach(c -> ((User) c).setLatestContactDeletion(Instant.now()));
+				}
+
+				group.getContacts()
+					.remove(persistenceManager.getUserByID(groupResize.get().getID()));
+				return;
 		}
-
-		// Update the group in the database
-		persistenceManager.updateContact(group);
-
-		// Send the updated group to all of its members
-		var commonGroup = group.toCommon();
-		group.getContacts()
-			.stream()
-			.map(Contact::getID)
-			.filter(connectionManager::isOnline)
-			.map(connectionManager::getSocketID)
-			.forEach(memberSocketID -> writeProxy.write(memberSocketID, commonGroup));
 	}
 }
diff --git a/server/src/main/java/envoy/server/processors/IDGeneratorRequestProcessor.java b/server/src/main/java/envoy/server/processors/IDGeneratorRequestProcessor.java
index 0cf9823..d3fe5db 100755
--- a/server/src/main/java/envoy/server/processors/IDGeneratorRequestProcessor.java
+++ b/server/src/main/java/envoy/server/processors/IDGeneratorRequestProcessor.java
@@ -4,6 +4,7 @@ import java.io.IOException;
 
 import envoy.data.IDGenerator;
 import envoy.event.IDGeneratorRequest;
+
 import envoy.server.data.*;
 import envoy.server.net.ObjectWriteProxy;
 
@@ -17,7 +18,8 @@ public final class IDGeneratorRequestProcessor implements ObjectProcessor<IDGene
 	private static final long ID_RANGE = 200;
 
 	@Override
-	public void process(IDGeneratorRequest input, long socketID, ObjectWriteProxy writeProxy) throws IOException {
+	public void process(IDGeneratorRequest input, long socketID, ObjectWriteProxy writeProxy)
+		throws IOException {
 		writeProxy.write(socketID, createIDGenerator());
 	}
 
@@ -25,7 +27,9 @@ public final class IDGeneratorRequestProcessor implements ObjectProcessor<IDGene
 	 * @return a new IDGenerator
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
-	public static IDGenerator createIDGenerator() { return createIDGenerator(ID_RANGE); }
+	public static IDGenerator createIDGenerator() {
+		return createIDGenerator(ID_RANGE);
+	}
 
 	/**
 	 * @param range of IDs used by the new IDGenerator
@@ -33,7 +37,8 @@ public final class IDGeneratorRequestProcessor implements ObjectProcessor<IDGene
 	 * @since Envoy Server Standalone v0.1-beta
 	 */
 	public static IDGenerator createIDGenerator(long range) {
-		ConfigItem	currentID	= PersistenceManager.getInstance().getConfigItemByID("currentMessageId");
+		ConfigItem	currentID	=
+			PersistenceManager.getInstance().getConfigItemByID("currentMessageId");
 		IDGenerator	generator	= new IDGenerator(Integer.parseInt(currentID.getValue()), range);
 		currentID.setValue(String.valueOf(Integer.parseInt(currentID.getValue()) + range));
 		PersistenceManager.getInstance().updateConfigItem(currentID);
diff --git a/server/src/main/java/envoy/server/processors/IsTypingProcessor.java b/server/src/main/java/envoy/server/processors/IsTypingProcessor.java
index aaf2987..1a0869c 100644
--- a/server/src/main/java/envoy/server/processors/IsTypingProcessor.java
+++ b/server/src/main/java/envoy/server/processors/IsTypingProcessor.java
@@ -3,6 +3,7 @@ package envoy.server.processors;
 import java.io.IOException;
 
 import envoy.event.IsTyping;
+
 import envoy.server.data.*;
 import envoy.server.net.*;
 
@@ -18,11 +19,14 @@ public final class IsTypingProcessor implements ObjectProcessor<IsTyping> {
 	private static final PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
 
 	@Override
-	public void process(IsTyping event, long socketID, ObjectWriteProxy writeProxy) throws IOException {
+	public void process(IsTyping event, long socketID, ObjectWriteProxy writeProxy)
+		throws IOException {
 		final var contact = persistenceManager.getContactByID(event.get());
 		if (contact instanceof User) {
 			final var destinationID = event.getDestinationID();
-			if (connectionManager.isOnline(destinationID)) writeProxy.write(connectionManager.getSocketID(destinationID), event);
-		} else writeProxy.writeToOnlineContacts(contact.getContacts(), event);
+			if (connectionManager.isOnline(destinationID))
+				writeProxy.write(connectionManager.getSocketID(destinationID), event);
+		} else
+			writeProxy.writeToOnlineContacts(contact.getContacts(), event);
 	}
 }
diff --git a/server/src/main/java/envoy/server/processors/IssueProposalProcessor.java b/server/src/main/java/envoy/server/processors/IssueProposalProcessor.java
index aa00ff1..cd3f857 100644
--- a/server/src/main/java/envoy/server/processors/IssueProposalProcessor.java
+++ b/server/src/main/java/envoy/server/processors/IssueProposalProcessor.java
@@ -7,12 +7,13 @@ import java.net.*;
 import java.util.logging.*;
 
 import envoy.event.IssueProposal;
-import envoy.server.net.ObjectWriteProxy;
 import envoy.util.EnvoyLog;
 
+import envoy.server.net.ObjectWriteProxy;
+
 /**
- * This processor handles incoming {@link IssueProposal}s and automatically
- * creates a new issue on the gitea site, if not disabled by its administrator.
+ * This processor handles incoming {@link IssueProposal}s and automatically creates a new issue on
+ * the gitea site, if not disabled by its administrator.
  *
  * @author Leon Hofmeister
  * @since Envoy Server v0.2-beta
@@ -22,9 +23,11 @@ public final class IssueProposalProcessor implements ObjectProcessor<IssuePropos
 	private static final Logger logger = EnvoyLog.getLogger(IssueProposalProcessor.class);
 
 	@Override
-	public void process(IssueProposal issueProposal, long socketID, ObjectWriteProxy writeProxy) throws IOException {
+	public void process(IssueProposal issueProposal, long socketID, ObjectWriteProxy writeProxy)
+		throws IOException {
 		// Do nothing if manually disabled
-		if (!config.isIssueReportingEnabled()) return;
+		if (!config.isIssueReportingEnabled())
+			return;
 		try {
 			final var	url			= new URL(config.getIssueReportingURL());
 			final var	connection	= (HttpURLConnection) url.openConnection();
@@ -41,18 +44,22 @@ public final class IssueProposalProcessor implements ObjectProcessor<IssuePropos
 			connection.setDoOutput(true);
 
 			final var json = String.format("{\"title\":\"%s\",\"body\":\"%s\",\"labels\":[%s, %s]}",
-					issueProposal.get(),
-					issueProposal.getDescription(),
-					config.getUserMadeLabel(),
-					issueProposal.isBug() ? config.getBugLabel() : config.getFeatureLabel());
+				issueProposal.get(),
+				issueProposal.getDescription(),
+				config.getUserMadeLabel(),
+				issueProposal.isBug() ? config.getBugLabel() : config.getFeatureLabel());
 			try (final var os = connection.getOutputStream()) {
 				final byte[] input = json.getBytes("utf-8");
 				os.write(input, 0, input.length);
 			}
 			final var status = connection.getResponseCode();
-			if (status == 201) logger.log(Level.INFO, "Successfully created an issue");
-			else logger.log(Level.WARNING,
-					String.format("Tried creating an issue for %s but received status code %d - Request params:%s", url, status, json));
+			if (status == 201)
+				logger.log(Level.INFO, "Successfully created an issue");
+			else
+				logger.log(Level.WARNING,
+					String.format(
+						"Tried creating an issue for %s but received status code %d - Request params:%s",
+						url, status, json));
 		} catch (final IOException e) {
 			logger.log(Level.WARNING, "An error occurred while creating an issue: ", e);
 		}
diff --git a/server/src/main/java/envoy/server/processors/LoginCredentialProcessor.java b/server/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
index 3e91a7f..e2f006b 100755
--- a/server/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
+++ b/server/src/main/java/envoy/server/processors/LoginCredentialProcessor.java
@@ -13,10 +13,12 @@ import javax.persistence.NoResultException;
 
 import envoy.data.LoginCredentials;
 import envoy.event.*;
+import envoy.event.contact.ContactsChangedSinceLastLogin;
+import envoy.util.*;
+
 import envoy.server.data.*;
 import envoy.server.net.*;
 import envoy.server.util.*;
-import envoy.util.*;
 
 /**
  * This {@link ObjectProcessor} handles {@link LoginCredentials}.
@@ -46,27 +48,29 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 
 		// Acquire a user object (or reject the handshake if that's impossible)
 		User user = null;
-		if (!credentials.isRegistration()) try {
-			user = persistenceManager.getUserByName(credentials.getIdentifier());
+		if (!credentials.isRegistration())
+			try {
+				user = persistenceManager.getUserByName(credentials.getIdentifier());
 
-			// Check if the user is already online
-			if (connectionManager.isOnline(user.getID())) {
-				logger.warning(user + " is already online!");
-				writeProxy.write(socketID, new HandshakeRejection(INTERNAL_ERROR));
-				return;
-			}
-
-			// Authenticate with password or token
-			if (credentials.usesToken()) {
-
-				// Check the token
-				if (user.getAuthToken() == null || user.getAuthTokenExpiration().isBefore(Instant.now())
-						|| !user.getAuthToken().equals(credentials.getPassword())) {
-					logger.info(user + " tried to use an invalid token.");
-					writeProxy.write(socketID, new HandshakeRejection(INVALID_TOKEN));
+				// Check if the user is already online
+				if (connectionManager.isOnline(user.getID())) {
+					logger.warning(user + " is already online!");
+					writeProxy.write(socketID, new HandshakeRejection(INTERNAL_ERROR));
 					return;
 				}
-			} else
+
+				// Authenticate with password or token
+				if (credentials.usesToken()) {
+
+					// Check the token
+					if (user.getAuthToken() == null
+						|| user.getAuthTokenExpiration().isBefore(Instant.now())
+						|| !user.getAuthToken().equals(credentials.getPassword())) {
+						logger.info(user + " tried to use an invalid token.");
+						writeProxy.write(socketID, new HandshakeRejection(INVALID_TOKEN));
+						return;
+					}
+				} else
 
 				// Check the password hash
 				if (!PasswordUtil.validate(credentials.getPassword(), user.getPasswordHash())) {
@@ -74,11 +78,11 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 					writeProxy.write(socketID, new HandshakeRejection(WRONG_PASSWORD_OR_USER));
 					return;
 				}
-		} catch (final NoResultException e) {
-			logger.info("The requested user does not exist.");
-			writeProxy.write(socketID, new HandshakeRejection(WRONG_PASSWORD_OR_USER));
-			return;
-		}
+			} catch (final NoResultException e) {
+				logger.info("The requested user does not exist.");
+				writeProxy.write(socketID, new HandshakeRejection(WRONG_PASSWORD_OR_USER));
+				return;
+			}
 		else {
 
 			// Validate user name
@@ -104,6 +108,7 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 				user.setStatus(ONLINE);
 				user.setPasswordHash(PasswordUtil.hash(credentials.getPassword()));
 				user.setContacts(new HashSet<>());
+				user.setLatestContactDeletion(Instant.EPOCH);
 				persistenceManager.addContact(user);
 				logger.info("Registered new " + user);
 			}
@@ -129,12 +134,14 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 				token = AuthTokenGenerator.nextToken();
 				user.setAuthToken(token);
 			}
-			user.setAuthTokenExpiration(Instant.now().plus(ServerConfig.getInstance().getAuthTokenExpiration().longValue(), ChronoUnit.DAYS));
+			user.setAuthTokenExpiration(Instant.now().plus(
+				ServerConfig.getInstance().getAuthTokenExpiration().longValue(), ChronoUnit.DAYS));
 			persistenceManager.updateContact(user);
 			writeProxy.write(socketID, new NewAuthToken(token));
 		}
 
-		final var pendingMessages = PersistenceManager.getInstance().getPendingMessages(user, credentials.getLastSync());
+		final var pendingMessages =
+			PersistenceManager.getInstance().getPendingMessages(user, credentials.getLastSync());
 		pendingMessages.removeIf(GroupMessage.class::isInstance);
 		logger.fine("Sending " + pendingMessages.size() + " pending messages to " + user + "...");
 
@@ -154,19 +161,24 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 				// Notify the sender about the delivery
 				if (connectionManager.isOnline(msg.getSender().getID())) {
 					msgCommon.nextStatus();
-					writeProxy.write(connectionManager.getSocketID(msg.getSender().getID()), new MessageStatusChange(msgCommon));
+					writeProxy.write(connectionManager.getSocketID(msg.getSender().getID()),
+						new MessageStatusChange(msgCommon));
 				}
-			} else writeProxy.write(socketID, new MessageStatusChange(msgCommon));
+			} else
+				writeProxy.write(socketID, new MessageStatusChange(msgCommon));
 		}
 
-		final List<GroupMessage> pendingGroupMessages = PersistenceManager.getInstance().getPendingGroupMessages(user, credentials.getLastSync());
-		logger.fine("Sending " + pendingGroupMessages.size() + " pending group messages to " + user + "...");
+		final List<GroupMessage> pendingGroupMessages = PersistenceManager.getInstance()
+			.getPendingGroupMessages(user, credentials.getLastSync());
+		logger.fine("Sending " + pendingGroupMessages.size() + " pending group messages to " + user
+			+ "...");
 
 		for (final var gmsg : pendingGroupMessages) {
 			final var gmsgCommon = gmsg.toCommon();
 
 			// Deliver the message to the user if he hasn't received it yet
-			if (gmsg.getCreationDate().isAfter(credentials.getLastSync()) || gmsg.getMemberMessageStatus().get(user.getID()) == SENT) {
+			if (gmsg.getCreationDate().isAfter(credentials.getLastSync())
+				|| gmsg.getMemberMessageStatus().get(user.getID()) == SENT) {
 				if (gmsg.getMemberMessageStatus().replace(user.getID(), RECEIVED) != RECEIVED) {
 
 					gmsg.setLastStatusChangeDate(Instant.now());
@@ -175,14 +187,15 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 
 					// Notify all online group members about the status change
 					writeProxy.writeToOnlineContacts(gmsg.getRecipient().getContacts(),
-							new GroupMessageStatusChange(gmsg.getID(), RECEIVED, Instant.now(), connectionManager.getUserIDBySocketID(socketID)));
+						new GroupMessageStatusChange(gmsg.getID(), RECEIVED, Instant.now(),
+							connectionManager.getUserIDBySocketID(socketID)));
 
 					if (Collections.min(gmsg.getMemberMessageStatus().values()) == RECEIVED) {
 						gmsg.received();
 
 						// Notify online members about the status change
 						writeProxy.writeToOnlineContacts(gmsg.getRecipient().getContacts(),
-								new MessageStatusChange(gmsg.getID(), gmsg.getStatus(), Instant.now()));
+							new MessageStatusChange(gmsg.getID(), gmsg.getStatus(), Instant.now()));
 					}
 
 					PersistenceManager.getInstance().updateMessage(gmsg);
@@ -193,18 +206,25 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 			} else {
 
 				// Sending group message status changes
-				if (gmsg.getStatus() == SENT && gmsg.getLastStatusChangeDate().isAfter(gmsg.getCreationDate())
-						|| gmsg.getStatus() == RECEIVED && gmsg.getLastStatusChangeDate().isAfter(gmsg.getReceivedDate()))
+				if (gmsg.getStatus() == SENT
+					&& gmsg.getLastStatusChangeDate().isAfter(gmsg.getCreationDate())
+					|| gmsg.getStatus() == RECEIVED
+						&& gmsg.getLastStatusChangeDate().isAfter(gmsg.getReceivedDate()))
 					gmsg.getMemberMessageStatus()
 						.forEach((memberID, memberStatus) -> writeProxy.write(socketID,
-								new GroupMessageStatusChange(gmsg.getID(), memberStatus, gmsg.getLastStatusChangeDate(), memberID)));
+							new GroupMessageStatusChange(gmsg.getID(), memberStatus,
+								gmsg.getLastStatusChangeDate(), memberID)));
 
 				// Deliver just a status change instead of the whole message
-				if (gmsg.getStatus() == RECEIVED && user.getLastSeen().isBefore(gmsg.getReceivedDate())
-						|| gmsg.getStatus() == READ && user.getLastSeen().isBefore(gmsg.getReadDate()))
+				if (gmsg.getStatus() == RECEIVED
+					&& user.getLastSeen().isBefore(gmsg.getReceivedDate())
+					|| gmsg.getStatus() == READ && user.getLastSeen().isBefore(gmsg.getReadDate()))
 					writeProxy.write(socketID, new MessageStatusChange(gmsgCommon));
 			}
 		}
+		// Notify the user if a contact deletion has happened since he last logged in
+		if (user.getLatestContactDeletion().isAfter(user.getLastSeen()))
+			writeProxy.write(socketID, new ContactsChangedSinceLastLogin());
 
 		// Complete the handshake
 		writeProxy.write(socketID, user.toCommon());
diff --git a/server/src/main/java/envoy/server/processors/MessageProcessor.java b/server/src/main/java/envoy/server/processors/MessageProcessor.java
index e7605d6..1681051 100755
--- a/server/src/main/java/envoy/server/processors/MessageProcessor.java
+++ b/server/src/main/java/envoy/server/processors/MessageProcessor.java
@@ -8,9 +8,10 @@ import javax.persistence.EntityExistsException;
 
 import envoy.data.Message;
 import envoy.event.*;
+import envoy.util.EnvoyLog;
+
 import envoy.server.data.PersistenceManager;
 import envoy.server.net.*;
-import envoy.util.EnvoyLog;
 
 /**
  * This {@link ObjectProcessor} handles incoming {@link Message}s.
@@ -23,7 +24,8 @@ public final class MessageProcessor implements ObjectProcessor<Message> {
 
 	private static final PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
 	private static final ConnectionManager	connectionManager	= ConnectionManager.getInstance();
-	private static final Logger				logger				= EnvoyLog.getLogger(MessageProcessor.class);
+	private static final Logger				logger				=
+		EnvoyLog.getLogger(MessageProcessor.class);
 
 	@Override
 	public void process(Message message, long socketID, ObjectWriteProxy writeProxy) {
diff --git a/server/src/main/java/envoy/server/processors/MessageStatusChangeProcessor.java b/server/src/main/java/envoy/server/processors/MessageStatusChangeProcessor.java
index 83f08fe..d954af5 100755
--- a/server/src/main/java/envoy/server/processors/MessageStatusChangeProcessor.java
+++ b/server/src/main/java/envoy/server/processors/MessageStatusChangeProcessor.java
@@ -5,9 +5,10 @@ import java.util.logging.*;
 
 import envoy.data.Message.MessageStatus;
 import envoy.event.MessageStatusChange;
+import envoy.util.EnvoyLog;
+
 import envoy.server.data.PersistenceManager;
 import envoy.server.net.*;
-import envoy.util.EnvoyLog;
 
 /**
  * @author Leon Hofmeister
@@ -17,10 +18,12 @@ public final class MessageStatusChangeProcessor implements ObjectProcessor<Messa
 
 	private final ConnectionManager		connectionManager	= ConnectionManager.getInstance();
 	private final PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
-	private final Logger				logger				= EnvoyLog.getLogger(MessageStatusChangeProcessor.class);
+	private final Logger				logger				=
+		EnvoyLog.getLogger(MessageStatusChangeProcessor.class);
 
 	@Override
-	public void process(MessageStatusChange statusChange, long socketID, ObjectWriteProxy writeProxy) throws IOException {
+	public void process(MessageStatusChange statusChange, long socketID,
+		ObjectWriteProxy writeProxy) throws IOException {
 
 		// Any other status than READ is not supposed to be sent to the server
 		if (statusChange.get() != MessageStatus.READ) {
@@ -34,6 +37,7 @@ public final class MessageStatusChangeProcessor implements ObjectProcessor<Messa
 
 		// Notifies the sender of the message about the status-update to READ
 		final long senderID = msg.getSender().getID();
-		if (connectionManager.isOnline(senderID)) writeProxy.write(connectionManager.getSocketID(senderID), statusChange);
+		if (connectionManager.isOnline(senderID))
+			writeProxy.write(connectionManager.getSocketID(senderID), statusChange);
 	}
 }
diff --git a/server/src/main/java/envoy/server/processors/NameChangeProcessor.java b/server/src/main/java/envoy/server/processors/NameChangeProcessor.java
index 7914c37..f89a324 100644
--- a/server/src/main/java/envoy/server/processors/NameChangeProcessor.java
+++ b/server/src/main/java/envoy/server/processors/NameChangeProcessor.java
@@ -3,6 +3,7 @@ package envoy.server.processors;
 import java.io.IOException;
 
 import envoy.event.NameChange;
+
 import envoy.server.data.*;
 import envoy.server.net.ObjectWriteProxy;
 
@@ -15,7 +16,8 @@ public final class NameChangeProcessor implements ObjectProcessor<NameChange> {
 	private static final PersistenceManager persistenceManager = PersistenceManager.getInstance();
 
 	@Override
-	public void process(NameChange nameChange, long socketID, ObjectWriteProxy writeProxy) throws IOException {
+	public void process(NameChange nameChange, long socketID, ObjectWriteProxy writeProxy)
+		throws IOException {
 		Contact toUpdate = persistenceManager.getContactByID(nameChange.getID());
 		toUpdate.setName(nameChange.get());
 		persistenceManager.updateContact(toUpdate);
diff --git a/server/src/main/java/envoy/server/processors/ObjectProcessor.java b/server/src/main/java/envoy/server/processors/ObjectProcessor.java
index cebd1f2..ffae6bd 100755
--- a/server/src/main/java/envoy/server/processors/ObjectProcessor.java
+++ b/server/src/main/java/envoy/server/processors/ObjectProcessor.java
@@ -5,8 +5,7 @@ import java.io.IOException;
 import envoy.server.net.ObjectWriteProxy;
 
 /**
- * This interface defines methods for processing objects of a specific
- * type incoming from a client.
+ * This interface defines methods for processing objects of a specific type incoming from a client.
  *
  * @author Kai S. K. Engelbart
  * @param <T> type of the request object
diff --git a/server/src/main/java/envoy/server/processors/PasswordChangeRequestProcessor.java b/server/src/main/java/envoy/server/processors/PasswordChangeRequestProcessor.java
index b275967..eb0f453 100644
--- a/server/src/main/java/envoy/server/processors/PasswordChangeRequestProcessor.java
+++ b/server/src/main/java/envoy/server/processors/PasswordChangeRequestProcessor.java
@@ -4,27 +4,34 @@ import java.io.IOException;
 import java.util.logging.Level;
 
 import envoy.event.*;
+import envoy.util.EnvoyLog;
+
 import envoy.server.data.PersistenceManager;
 import envoy.server.net.ObjectWriteProxy;
 import envoy.server.util.PasswordUtil;
-import envoy.util.EnvoyLog;
 
 /**
  * @author Leon Hofmeister
  * @since Envoy Server v0.2-beta
  */
-public final class PasswordChangeRequestProcessor implements ObjectProcessor<PasswordChangeRequest> {
+public final class PasswordChangeRequestProcessor
+	implements ObjectProcessor<PasswordChangeRequest> {
 
 	@Override
-	public void process(PasswordChangeRequest event, long socketID, ObjectWriteProxy writeProxy) throws IOException {
+	public void process(PasswordChangeRequest event, long socketID, ObjectWriteProxy writeProxy)
+		throws IOException {
 		final var	persistenceManager		= PersistenceManager.getInstance();
 		final var	user					= persistenceManager.getUserByID(event.getID());
-		final var	logger					= EnvoyLog.getLogger(PasswordChangeRequestProcessor.class);
-		final var	correctAuthentication	= PasswordUtil.validate(event.getOldPassword(), user.getPasswordHash());
+		final var	logger					=
+			EnvoyLog.getLogger(PasswordChangeRequestProcessor.class);
+		final var	correctAuthentication	=
+			PasswordUtil.validate(event.getOldPassword(), user.getPasswordHash());
 		if (correctAuthentication) {
 			user.setPasswordHash(PasswordUtil.hash(event.get()));
 			logger.log(Level.INFO, user + " changed his password");
-		} else logger.log(Level.INFO, user + " tried changing his password but provided insufficient authentication");
+		} else
+			logger.log(Level.INFO,
+				user + " tried changing his password but provided insufficient authentication");
 		writeProxy.write(socketID, new PasswordChangeResult(correctAuthentication));
 	}
 }
diff --git a/server/src/main/java/envoy/server/processors/ProfilePicChangeProcessor.java b/server/src/main/java/envoy/server/processors/ProfilePicChangeProcessor.java
index 112170c..8b97147 100644
--- a/server/src/main/java/envoy/server/processors/ProfilePicChangeProcessor.java
+++ b/server/src/main/java/envoy/server/processors/ProfilePicChangeProcessor.java
@@ -3,6 +3,7 @@ package envoy.server.processors;
 import java.io.IOException;
 
 import envoy.event.ProfilePicChange;
+
 import envoy.server.net.ObjectWriteProxy;
 
 /**
@@ -12,5 +13,6 @@ import envoy.server.net.ObjectWriteProxy;
 public final class ProfilePicChangeProcessor implements ObjectProcessor<ProfilePicChange> {
 
 	@Override
-	public void process(ProfilePicChange event, long socketID, ObjectWriteProxy writeProxy) throws IOException {}
+	public void process(ProfilePicChange event, long socketID, ObjectWriteProxy writeProxy)
+		throws IOException {}
 }
diff --git a/server/src/main/java/envoy/server/processors/UserOperationProcessor.java b/server/src/main/java/envoy/server/processors/UserOperationProcessor.java
new file mode 100755
index 0000000..d03d1d4
--- /dev/null
+++ b/server/src/main/java/envoy/server/processors/UserOperationProcessor.java
@@ -0,0 +1,57 @@
+package envoy.server.processors;
+
+import java.time.Instant;
+import java.util.logging.*;
+
+import envoy.event.ElementOperation;
+import envoy.event.contact.UserOperation;
+import envoy.util.EnvoyLog;
+
+import envoy.server.data.PersistenceManager;
+import envoy.server.net.*;
+
+/**
+ * @author Kai S. K. Engelbart
+ * @since Envoy Server Standalone v0.1-alpha
+ */
+public final class UserOperationProcessor implements ObjectProcessor<UserOperation> {
+
+	private static final ConnectionManager	connectionManager	= ConnectionManager.getInstance();
+	private static final Logger				logger				=
+		EnvoyLog.getLogger(UserOperationProcessor.class);
+	private static final PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
+
+	@Override
+	public void process(UserOperation evt, long socketId, ObjectWriteProxy writeProxy) {
+		final long	userID		= ConnectionManager.getInstance().getUserIDBySocketID(socketId);
+		final long	contactID	= evt.get().getID();
+		final var	sender		= persistenceManager.getUserByID(userID);
+		switch (evt.getOperationType()) {
+			case ADD:
+				logger.log(Level.FINE,
+					String.format("Adding %s to the contact list of user %d.", evt.get(), userID));
+				persistenceManager.addContactBidirectional(userID, contactID);
+
+				// Notify the contact if online
+				if (connectionManager.isOnline(contactID))
+					writeProxy.write(connectionManager.getSocketID(contactID),
+						new UserOperation(sender.toCommon(), ElementOperation.ADD));
+				break;
+			case REMOVE:
+
+				// Remove the relationships and notify sender if he logs in using another
+				// LocalDB
+				persistenceManager.removeContactBidirectional(userID, contactID);
+				sender.setLatestContactDeletion(Instant.now());
+
+				// Notify the removed contact on next startup(s) of this deletion
+				persistenceManager.getUserByID(contactID).setLatestContactDeletion(Instant.now());
+
+				// Notify the removed contact if online
+				if (connectionManager.isOnline(contactID))
+					writeProxy.write(connectionManager.getSocketID(contactID),
+						new UserOperation(sender.toCommon(), ElementOperation.REMOVE));
+				break;
+		}
+	}
+}
diff --git a/server/src/main/java/envoy/server/processors/UserSearchProcessor.java b/server/src/main/java/envoy/server/processors/UserSearchProcessor.java
index 7166d6a..c1d6c37 100755
--- a/server/src/main/java/envoy/server/processors/UserSearchProcessor.java
+++ b/server/src/main/java/envoy/server/processors/UserSearchProcessor.java
@@ -5,6 +5,7 @@ import java.util.stream.Collectors;
 
 import envoy.data.Contact;
 import envoy.event.contact.*;
+
 import envoy.server.data.*;
 import envoy.server.net.*;
 
@@ -16,19 +17,21 @@ import envoy.server.net.*;
 public final class UserSearchProcessor implements ObjectProcessor<UserSearchRequest> {
 
 	/**
-	 * Writes a list of contacts to the client containing all {@link Contact}s
-	 * matching the search phrase contained inside the request. The client and their
-	 * contacts are excluded from the result.
+	 * Writes a list of contacts to the client containing all {@link Contact}s matching the search
+	 * phrase contained inside the request. The client and their contacts are excluded from the
+	 * result.
 	 *
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
 	@Override
-	public void process(UserSearchRequest request, long socketID, ObjectWriteProxy writeProxy) throws IOException {
+	public void process(UserSearchRequest request, long socketID, ObjectWriteProxy writeProxy)
+		throws IOException {
 		writeProxy.write(socketID,
-				new UserSearchResult(PersistenceManager.getInstance()
-					.searchUsers(request.get(), ConnectionManager.getInstance().getUserIDBySocketID(socketID))
-					.stream()
-					.map(User::toCommon)
-					.collect(Collectors.toList())));
+			new UserSearchResult(PersistenceManager.getInstance()
+				.searchUsers(request.get(),
+					ConnectionManager.getInstance().getUserIDBySocketID(socketID))
+				.stream()
+				.map(User::toCommon)
+				.collect(Collectors.toList())));
 	}
 }
diff --git a/server/src/main/java/envoy/server/processors/UserStatusChangeProcessor.java b/server/src/main/java/envoy/server/processors/UserStatusChangeProcessor.java
index c551513..427bb55 100755
--- a/server/src/main/java/envoy/server/processors/UserStatusChangeProcessor.java
+++ b/server/src/main/java/envoy/server/processors/UserStatusChangeProcessor.java
@@ -4,9 +4,10 @@ import java.util.logging.Logger;
 
 import envoy.data.User.UserStatus;
 import envoy.event.UserStatusChange;
+import envoy.util.EnvoyLog;
+
 import envoy.server.data.*;
 import envoy.server.net.ObjectWriteProxy;
-import envoy.util.EnvoyLog;
 
 /**
  * This processor handles incoming {@link UserStatusChange}.
@@ -19,7 +20,8 @@ public final class UserStatusChangeProcessor implements ObjectProcessor<UserStat
 	private static ObjectWriteProxy writeProxy;
 
 	private static final PersistenceManager	persistenceManager	= PersistenceManager.getInstance();
-	private static final Logger				logger				= EnvoyLog.getLogger(UserStatusChangeProcessor.class);
+	private static final Logger				logger				=
+		EnvoyLog.getLogger(UserStatusChangeProcessor.class);
 
 	@Override
 	public void process(UserStatusChange input, long socketID, ObjectWriteProxy writeProxy) {
@@ -32,8 +34,8 @@ public final class UserStatusChangeProcessor implements ObjectProcessor<UserStat
 	}
 
 	/**
-	 * Sets the {@link UserStatus} for a given user. Both offline contacts and
-	 * currently online contacts are notified.
+	 * Sets the {@link UserStatus} for a given user. Both offline contacts and currently online
+	 * contacts are notified.
 	 *
 	 * @param user      the user whose status has changed
 	 * @param newStatus the new status of that user
@@ -47,19 +49,21 @@ public final class UserStatusChangeProcessor implements ObjectProcessor<UserStat
 		persistenceManager.updateContact(user);
 
 		// Handling for contacts that are already online
-		writeProxy.writeToOnlineContacts(user.getContacts(), new UserStatusChange(user.getID(), user.getStatus()));
+		writeProxy.writeToOnlineContacts(user.getContacts(),
+			new UserStatusChange(user.getID(), user.getStatus()));
 	}
 
 	/**
-	 * This method is only called by the LoginCredentialProcessor because every
-	 * user needs to login (open a socket) before changing his status.
-	 * Needed to ensure propagation of events because an uninitialized writeProxy
-	 * would cause problems.
+	 * This method is only called by the LoginCredentialProcessor because every user needs to login
+	 * (open a socket) before changing his status. Needed to ensure propagation of events because an
+	 * uninitialized writeProxy would cause problems.
 	 *
 	 * @param writeProxy the writeProxy that is used to send objects back to clients
 	 * @since Envoy Server Standalone v0.1-alpha
 	 */
-	public static void setWriteProxy(ObjectWriteProxy writeProxy) { UserStatusChangeProcessor.writeProxy = writeProxy; }
+	public static void setWriteProxy(ObjectWriteProxy writeProxy) {
+		UserStatusChangeProcessor.writeProxy = writeProxy;
+	}
 	// TODO may cause an problem if two clients log in at the same time.
 	// Change Needed.
 }
diff --git a/server/src/main/java/envoy/server/processors/package-info.java b/server/src/main/java/envoy/server/processors/package-info.java
index d96d161..58b93dd 100755
--- a/server/src/main/java/envoy/server/processors/package-info.java
+++ b/server/src/main/java/envoy/server/processors/package-info.java
@@ -1,6 +1,5 @@
 /**
- * This package contains all classes that process data received from client
- * connections.
+ * This package contains all classes that process data received from client connections.
  *
  * @author Kai S. K. Engelbart
  * @author Leon Hofmeister
diff --git a/server/src/main/java/envoy/server/util/AuthTokenGenerator.java b/server/src/main/java/envoy/server/util/AuthTokenGenerator.java
index c6fc928..c6cf6af 100644
--- a/server/src/main/java/envoy/server/util/AuthTokenGenerator.java
+++ b/server/src/main/java/envoy/server/util/AuthTokenGenerator.java
@@ -11,7 +11,8 @@ import java.security.SecureRandom;
 public final class AuthTokenGenerator {
 
 	private static final int			TOKEN_LENGTH	= 128;
-	private static final char[]			CHARACTERS		= "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();
+	private static final char[]			CHARACTERS		=
+		"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();
 	private static final char[]			BUFF			= new char[TOKEN_LENGTH];
 	private static final SecureRandom	RANDOM			= new SecureRandom();
 
diff --git a/server/src/main/java/envoy/server/util/PasswordUtil.java b/server/src/main/java/envoy/server/util/PasswordUtil.java
index 80ba6c1..557707d 100644
--- a/server/src/main/java/envoy/server/util/PasswordUtil.java
+++ b/server/src/main/java/envoy/server/util/PasswordUtil.java
@@ -7,9 +7,9 @@ import javax.crypto.SecretKeyFactory;
 import javax.crypto.spec.PBEKeySpec;
 
 /**
- * Provides a password hashing and comparison mechanism using the
- * {@code PBKDF2WithHmacSHA1} algorithm.
- * 
+ * Provides a password hashing and comparison mechanism using the {@code PBKDF2WithHmacSHA1}
+ * algorithm.
+ *
  * @author Kai S. K. Engelbart
  * @since Envoy Server Standalone v0.1-beta
  */
@@ -37,7 +37,8 @@ public final class PasswordUtil {
 			byte[]		salt		= fromHex(parts[1]);
 			byte[]		hash		= fromHex(parts[2]);
 
-			var		spec		= new PBEKeySpec(current.toCharArray(), salt, iterations, KEY_LENGTH);
+			var		spec		=
+				new PBEKeySpec(current.toCharArray(), salt, iterations, KEY_LENGTH);
 			var		skf			= SecretKeyFactory.getInstance(SECRET_KEY_ALGORITHM);
 			byte[]	testHash	= skf.generateSecret(spec).getEncoded();
 
@@ -53,7 +54,7 @@ public final class PasswordUtil {
 
 	/**
 	 * Creates a parameterized salted password hash.
-	 * 
+	 *
 	 * @param password the password to hash
 	 * @return a result string in the form of {@code iterations:salt:hash}
 	 * @since Envoy Server Standalone v0.1-beta
diff --git a/server/src/main/java/envoy/server/util/VersionUtil.java b/server/src/main/java/envoy/server/util/VersionUtil.java
index 907b78f..9cb8dac 100644
--- a/server/src/main/java/envoy/server/util/VersionUtil.java
+++ b/server/src/main/java/envoy/server/util/VersionUtil.java
@@ -3,8 +3,8 @@ package envoy.server.util;
 import java.util.regex.Pattern;
 
 /**
- * Implements a comparison algorithm between Envoy versions and defines minimal
- * and maximal client versions compatible with this server.
+ * Implements a comparison algorithm between Envoy versions and defines minimal and maximal client
+ * versions compatible with this server.
  *
  * @author Kai S. K. Engelbart
  * @since Envoy Server Standalone v0.1-beta
@@ -25,13 +25,14 @@ public final class VersionUtil {
 	 */
 	public static final String MAX_CLIENT_VERSION = "0.2-beta";
 
-	private static final Pattern versionPattern = Pattern.compile("(?<major>\\d).(?<minor>\\d)(?:-(?<suffix>\\w+))?");
+	private static final Pattern versionPattern =
+		Pattern.compile("(?<major>\\d).(?<minor>\\d)(?:-(?<suffix>\\w+))?");
 
 	private VersionUtil() {}
 
 	/**
-	 * Parses an Envoy Client version string and checks whether that version is
-	 * compatible with this server.
+	 * Parses an Envoy Client version string and checks whether that version is compatible with this
+	 * server.
 	 *
 	 * @param version the version string to parse
 	 * @return {@code true} if the given version is compatible with this server
@@ -40,12 +41,14 @@ public final class VersionUtil {
 	public static boolean verifyCompatibility(String version) {
 		final var currentMatcher = versionPattern.matcher(version);
 
-		if (!currentMatcher.matches()) return false;
+		if (!currentMatcher.matches())
+			return false;
 
 		final var	minMatcher	= versionPattern.matcher(MIN_CLIENT_VERSION);
 		final var	maxMatcher	= versionPattern.matcher(MAX_CLIENT_VERSION);
 
-		if (!minMatcher.matches() || !maxMatcher.matches()) throw new RuntimeException("Invalid min or max client version configured!");
+		if (!minMatcher.matches() || !maxMatcher.matches())
+			throw new RuntimeException("Invalid min or max client version configured!");
 
 		// Compare suffixes
 		{
@@ -53,7 +56,8 @@ public final class VersionUtil {
 			final var	minSuffix		= convertSuffix(minMatcher.group("suffix"));
 			final var	maxSuffix		= convertSuffix(maxMatcher.group("suffix"));
 
-			if (currentSuffix < minSuffix || currentSuffix > maxSuffix) return false;
+			if (currentSuffix < minSuffix || currentSuffix > maxSuffix)
+				return false;
 		}
 
 		// Compare major
@@ -62,7 +66,8 @@ public final class VersionUtil {
 			final var	minMajor		= Integer.parseInt(minMatcher.group("major"));
 			final var	maxMajor		= Integer.parseInt(maxMatcher.group("major"));
 
-			if (currentMajor < minMajor || currentMajor > maxMajor) return false;
+			if (currentMajor < minMajor || currentMajor > maxMajor)
+				return false;
 		}
 
 		// Compare minor
@@ -71,7 +76,8 @@ public final class VersionUtil {
 			final var	minMinor		= Integer.parseInt(minMatcher.group("minor"));
 			final var	maxMinor		= Integer.parseInt(maxMatcher.group("minor"));
 
-			if (currentMinor < minMinor || currentMinor > maxMinor) return false;
+			if (currentMinor < minMinor || currentMinor > maxMinor)
+				return false;
 		}
 
 		return true;
diff --git a/server/src/main/java/envoy/server/util/package-info.java b/server/src/main/java/envoy/server/util/package-info.java
index 3cfc809..706fae8 100644
--- a/server/src/main/java/envoy/server/util/package-info.java
+++ b/server/src/main/java/envoy/server/util/package-info.java
@@ -1,6 +1,6 @@
 /**
  * This package contains utility classes used in Envoy Server.
- * 
+ *
  * @author Kai S. K. Engelbart
  * @since Envoy Server Standalone v0.1-beta
  */
diff --git a/server/src/main/java/module-info.java b/server/src/main/java/module-info.java
index 7707142..221d471 100755
--- a/server/src/main/java/module-info.java
+++ b/server/src/main/java/module-info.java
@@ -1,6 +1,5 @@
 /**
- * This module contains all classes defining the server application of the Envoy
- * project.
+ * This module contains all classes defining the server application of the Envoy project.
  *
  * @author Kai S. K. Engelbart
  * @author Leon Hofmeister